1. Introduction
Many factors can influence a consumer’s desire to purchase environmentally friendly products. A literature review of 108 articles across the six years from 2015 to 2021 revealed that perceived consumer effectiveness, customers’ attitudes, subjective norms, environmental concerns, environmental knowledge, perceived behavioral control, and awareness were considered the major positive factors of both green product intention and behavior. Meanwhile, price, health consciousness, and green trust as well as intention, environmental involvement, and personal norms emerged as major positive drivers for green product intention and behavior, respectively [
1]. Next, previous research has found that environmental knowledge [
2], word of mouth (WOM) [
3,
4,
5], green marketing [
6], and environmental care attitudes [
7,
8] all influence purchase intention. Knowledge can influence people’s desire for environmentally friendly products. Furthermore, understanding consumer attitudes and beliefs toward environmentally friendly products raises consumer awareness of the environment [
9]. Additionally, knowledge is important, but it is influenced by the knowledge of others who have used green products, known as WOM. WOM has the potential to spread faster than advertising or direct mail [
10]. Research has also shown that green marketing positively influences purchasing decisions [
11]. Although green marketing has been a major research topic for decades, little research [
12,
13,
14] has focused on the effect of green marketing strategies on purchasing intention, especially in developing countries.
Of all previous studies, research focusing on word-of-mouth and green marketing as drivers of green product intentions and behaviors is still relatively limited and thus deserves further research. An obvious research gap in this study is that none of the studies above analyzed all variables, namely knowledge, WOM, and green marketing, at once. Therefore, this research might allow the identification of multiple variables encouraging or obstructing green product attitudes and intentions. Therefore, this study contributes to the literature that examines the driving factors of behavioral intentions for green products, whether the most influential factor is internal or external to the consumer. Moreover, this research might assist in clarifying the different causes behind the existing green product intention inconsistency and the elements accountable for such conflicting behavior. So, this research aims to bridge the gap between how customers think and behave about green products, and research often shows a dissonance between the status of customers and their actual behavior regarding sustainable behavior [
15]. This phenomenon is well-known in previous literature and has been called the “green attitude–behavior gap” [
16]. This finding is a useful contribution towards the formation of green product interest because an increasing number of people are concerned about environmental issues, eventually leading to increased demand for eco-friendly products in daily behavior. Moreover, marketers must understand consumers’ willingness to purchase green products [
17], which helps formulate appropriate green product market development strategies.
Two theories are relevant to this study: ABC theory and norm activation model (NAM) theory. These two theories emphasize that ABC theory and norm activation models can effectively explain and predict environmentally conscious behavior based on the idea that cognitive and moral norms determine what people believe and behave as environmentally conscious consumers. First, the ABC theory posits that attitudes describe ambivalence’s emotional, cognitive, and physical consequences, which influence how different components interact [
18]. According to ABC theory, what is affected is a person’s emotions, attitudes, and sympathetic nervous system activity associated with objects and their association [
19]. Other aspects of cognition also influence attitudes; a person’s understanding of and opinion about the attitude object is derived from their feelings toward the attitude object [
20]. In addition, according to the NAM theory, personal norms are based on two factors: awareness of whether or not a behavior has consequences and a sense of responsibility for carrying out certain behaviors. It explains that awareness of consequences affects personal norms via a person’s responsibilities. Therefore, awareness of consequences and responsibilities moderates the influence of personal norms on behavior [
21].
The goals of this study are first to describe each research variable in detail and second to analyze the effect of environmental knowledge, WOM, and green marketing on attitudes toward environmental care and the intention to purchase green products.
The theoretical model of the research was built in the framework depicted in
Figure 1 using the ABC theory and the NAM theory.
Based on the framework in
Figure 1, the following hypotheses are proposed:
H1: Environmental knowledge significantly affects environmental care attitudes.
Knowledge may be crucial in motivating one’s behavioral change to engage in general pro-environmental behavior [
22]. Consumers who understand the concept of environmentally friendly products, the awareness of consuming environmentally friendly products, and the environmental regulations will consider the environmentally friendly value of a product before deciding to buy. In addition, environmental knowledge can influence environmentally friendly attitudes [
9]. Consumers with a high level of environmental knowledge have a good attitude toward environmental protection and a strong willingness to buy green products [
23].
H2: WOM significantly affects the attitude toward environmental care.
Word of mouth is defined as a promotional medium through the exchange, information flow, communication, or conversation between two individuals related to the value of a good/service that has been purchased or used, thus impacting the assessment of the good/service [
24]. Word of mouth can influence the perception of others after hearing or reading a judgment about something, for example, a green consumer’s review [
3].
H3: Green marketing significantly influences people’s attitudes toward environmental protection.
Green marketing is the process of marketing products in an environmentally friendly way, reducing the use of raw materials that damage the environment [
25]. Previous researchers such as [
12,
13,
14] found that green marketing has been extensively researched in western countries, while little research has been conducted on green purchasing behavior in developing countries, including Indonesia. Previous research revealed a positive and significant influence between green marketing variables on purchase intention variables and also shows that green marketing strategies on products can generate interest in potential consumers in these products. Green marketing positively and significantly influences purchasing intentions for green products [
26]. Furthermore, several eco-labels and customer feedback, as part of green marketing, influence customers’ willingness to spend more on green products [
18,
19,
27]. Moreover, green marketing activities can better promote the positive impact of corporate green marketing behaviors on consumers’ willingness to consume green [
28].
H4: Environmental knowledge significantly affects the purchase intention of green products.
Environmental knowledge can be an important factor influencing purchase intention towards green products. Previous research states that environmental knowledge can influence consumer intention and behavior in buying green products [
29]. Environmental knowledge is also an indicator of each individual’s social and environmental sustainability, and this attitude provides an impetus for buying interest in green products [
7]. Furthermore, the results of previous studies explain that environmental knowledge positively affects green product purchase intentions [
30]. In addition, green brand knowledge was the most significant determinant of green product purchase intention [
31].
H5: WOM significantly influences the purchase intention of green products.
Word of mouth plays a major role in creating an image in the minds of consumers, which can cause consumers to be interested in buying the product through word of mouth. Previous research found that word of mouth significantly affects brand image [
32]. The results of previous research also concluded that word of mouth could influence trust, thus impacting consumer purchase intention [
33]. Previous research also states that the impact of word of mouth is very strong on consumers and can result in changes in purchasing interests and decisions [
34].
H6: Green marketing significantly affects the purchase intention of green products.
Green marketing offers will likely trigger interest in buying the product. The green marketing mix (green products, prices, places, and advertisements) significantly correlates with purchase intention [
35]. From a green marketing point of view, consumers negotiate morals subjectively, thus causing a min-at to buy green products [
36]. One of the importances of implementing green marketing is that it can make differentiation for a product in an increasingly changing market; this can increase public interest in buying green products or environmentally friendly products. Consumers with a positive attitude towards green brands will have a high chance of making purchases; green brands significantly affect green purchase intention [
37]. As a green marketing tool, various channels affect consumers’ psychological feelings when providing psychological security, making consumers trust products and leading to behavioral purchase intentions for consumers [
38].
H7: Environmental care attitude has a significant effect on green product purchase intention.
Concern for the environment and climate is an individual’s moral obligation to do something for the environment [
39]. Therefore, environmental concerns reflected in environmental care attitudes significantly positively affect the purchase intention of green products [
40,
41]. Next, using the PLS-SEM method, the scholar concluded that attitude plays a significant role in consumers’ intention to buy green cosmetics in Indonesia [
42]. In addition, the role of consumer attitudes has a significant effect on the repurchase intention of environmentally friendly products [
2].
2. Materials and Methods
This research applied a quantitative approach using online survey techniques to examine the impact of environmental knowledge, WOM, and green marketing on environmental care attitudes and green product purchase intentions. Data were collected via Google Forms, and information was disseminated via the social media WhatsApp, Line, and Instagram. However, how much data were obtained from each social media platform was unclear.
Furthermore, a voluntary sampling of Indonesian citizens was used based on the respondent’s desire to participate. As the name implies, the final sample is selected from those potential respondents willing and eligible to participate in the survey. The sample size is based on 5–10 times the number of variables [
43]. Because there are 27 indicators in this study, the sample size required is 135–270 participants. A total of 159 valid questionnaires were analyzed. According to the demographics of the respondents, six out of ten are females aged 21–30 years who live in Greater Jakarta. In addition, four out of ten respondents had completed senior high school. Furthermore, four out of ten graduated from senior high school and are now undergraduate students. Almost 40% of respondents have an average monthly income of more than 1,000,000 rupiahs. The sample characteristics were obtained as shown in
Table 1.
The variables observed in this study consisted of five components, all measured using modified instruments derived from previous studies. Environmental knowledge [
44], WOM [
3], green marketing [
6], environmental care attitude [
7], and the intention to purchase green products [
45] are among these factors. The instrument was also modified to make it more understandable and simpler to complete using a five-point Likert scale. In addition, this study adds one indicator in the purchase intention of green products, namely MB4.
Table 2 lists the latent variables, codes, variable indicators, and scales.
Instrument testing was performed before data collection to ensure a reliable measuring device. This study included 34 participants. The data were also analyzed using Cronbach’s alpha statistic. A variable is considered reliable if its Cronbach’s alpha value is greater than 0.60. The reliability test results demonstrate that each variable has a Cronbach’s alpha value of ≥0.6, indicating that each question on the five variables used in this study is reliable (
Table 3).
Descriptive statistics were performed first to address the first goal of identifying each research variable. The average score of each indicator in a single variable was summed and then converted into an index (0–100 scale). The objective is for each variable to have the same comparison. The classification of the index is determined by categorizing it as low (index ≤ 60.00), moderate (index 60.01–79.99), and high (index ≥ 80.00). The index was calculated using the following formula:
A structural equation modeling (SEM) analysis with LISREL was used to address the second objective: to examine the effects of environmental knowledge, WOM, green marketing, and environmental care attitudes on the purchase intention of green products.
4. Discussion
4.1. The Effect of Environmental Knowledge on Environmental Care Attitudes (H1)
The findings revealed that environmental awareness significantly impacts the attitude toward environmental care. The coefficient of environmental knowledge on environmental care attitudes of 0.20 and a t-value of 2.03 support this conclusion. A value greater than 1.96 indicates a significant and positive relationship. The following indicators are part of environmental knowledge, with understanding global warming (PL1) being one of the most significant indicators with a loading factor of 0.93. This result implies that understanding global warming will significantly impact increasing environmental awareness.
Thus, H1 has been proven and accepted. Environmental knowledge affects environmental care attitudes by 20%. The greater one’s environmental knowledge, the more positive one’s attitude toward environmental stewardship. This finding implies that someone with extensive environmental knowledge will influence their thoughts and opinions about the environment. This will be reflected in a considerate attitude toward the environment. Attitudes based on a comprehensive and organized knowledge base could be the foundation for reactions to attitudes [
46]. Knowledge is required to understand the principles of sustainable development, their implementation, the attitudes and values associated with them, and the consequences of their application [
47]. Furthermore, understanding consumer attitudes and beliefs about environmentally friendly products is the primary driver of environmentally conscious consumer behavior. Consumers with higher environmental awareness and concern have a more ecological attitude than consumers without awareness or concern. This finding demonstrates that the more consumers know about the environment, the more environmentally conscious they are.
4.2. The Effect of Word of Mouth on Environmental Care Attitudes (H2)
The WOM does not affect environmental care attitudes. This is supported by the t-values of 1.45. This value is less than 1.96, indicating no significant influence exists between variables. Thus, H2 is rejected. The reviews from others do not affect a person’s attitude. The tendency to listen to or see comments from other people to find out about a product or service, such as consulting with other consumers to help choose the right product, gathering information about product reviews from other consumers before buying a particular product, did not give the consumers the confidence to buy the product.
The opinions of friends, the government, and environmental organizations might be more influenced by environmental care attitudes [
3]. These findings are possible because other people’s product reviews are less significant and do not draw attention to the product to be used. Therefore, someone who reads or hears product reviews is more concerned with the advantages and disadvantages that the reviewer experienced after purchasing the product.
4.3. The Effect of Green Marketing on Environmental Care Attitudes (H3)
The analysis results conclude that green marketing does not affect environmental care attitudes. The
t-value of less than 1.96, equal to 1.31, supports this conclusion, indicating no significant effect between the variables. Therefore, H3 was rejected. In addition, the path coefficient value of green marketing’s influence on environmental care attitude is 0.15, indicating that an increase in green marketing’s attitude does not lead to an increase in environmental care attitude. This study’s finding contradicts previous research, which found that the attractiveness of advertisements significantly impacts people’s attitudes toward green brands [
48].
The green marketing to promote a product as environmentally friendly and reducing the use of polluting raw materials applied by companies has not succeeded in increasing the positive environmental care attitudes. Respondents’ assumed the company’s green marketing did not include values encouraging consumers to be environmentally friendly.
4.4. The Effect of Environmental Knowledge on Intention to Purchase Green Products (H4)
Environmental knowledge does not affect purchase intention for green products. This is supported by the
t-values of 1.08. This value is less than 1.96, indicating no significant relationship between variables. Thus, H4 is rejected. This study’s findings contradict previous research, which found that environmental knowledge issues significantly impact the desire and choice to consume green products [
30]. The greater a consumer’s environmental knowledge, the less they will feel responsible for environmental pollution, the greenhouse effect, and air quality. Even though purchasing green products is wise, switching to green products has numerous advantages.
Environmental knowledge in green products does not reflect customer commitment to prefer green products over conventional products [
49]. Consumers familiar with the environment are less interested in green purchasing. This implies that respondents in this study are thought to believe that environmental knowledge is not a major factor in encouraging interest in purchasing green products. Knowledge about the environment has a greater influence on consumer mindsets, but it has not yet reached the stage of influencing the desire to purchase a product because other factors can influence purchasing interest.
4.5. The Effect of Word of Mouth on Intention to Purchase Green Products (H5)
The findings revealed that WOM did not affect purchase intentions for green products. This is supported by the
t-values of 1.16. However, this value is less than 1.96, indicating no significant influence exists between variables. Thus, H5 is rejected. The tendency to listen to or see other people’s comments to find out about a product or service had no impact on a person’s interest in purchasing green products. This finding contradicts the previous research, which demonstrated that electronic WOM has a significant effect on purchase intention [
50,
51]. Respondents in this study are suspected of assuming that reviews obtained from other consumers are not a significant factor in encouraging interest in purchasing green products. This result is possible because WOM is an external factor and thus has less clout than other factors.
4.6. The Effect of Green Marketing on Intention to Purchase Green Products (H6)
The results show that the path coefficient value of green marketing on green product purchase intention is 0.54 with a t-value of 4.90. This result affects why green marketing has a significant positive impact on green product purchase intentions. Thus, this study’s H6 is proven and accepted. Respondents always consider products that use environmentally friendly packaging. They believe green marketing through environmentally friendly packaging affects their purchasing interest in green products.
The more interested respondents are in corporate green marketing, the more interested they are in purchasing green products. Respondents realized that a company’s green marketing could entice consumers to buy the products offered. This is in line with the previous research showing that environmental consumer attitudes influence consumers’ willingness to purchase environmentally friendly products [
52].
4.7. The Effect of Environmental Care Attitudes on Intention to Purchase Green Products (H7)
The result revealed that the path coefficient value of green marketing on buying interest in green products is 0.17, with a t-value of 1.99. This finding affects why environmental care attitude significantly impacts green product purchase intention. Thus, H7 is proven and accepted. The respondents’ feeling of responsibility for environmental pollution will contribute to positive environmental care attitudes. These data illustrate that respondents believe that being responsible for environmental pollution affects their interest in purchasing green products. For consumers who feel responsible for environmental pollution, the greenhouse effect, and air quality, purchasing green products is a wise choice. They consider switching to green products because of the many benefits such as less pollution. Moreover, because they care about the environment, they switch from regular to green products for ecological reasons, plan to consume green products, and continue to buy them even though they are expensive. The more concerned people are about environmental sustainability, the more interested they are in purchasing green products.
Overall, respondents who already have environmental care attitudes can increase consumer interest in purchasing green products as proven by previous research of [
53]. Furthermore, this study is consistent with the NAM theory, which states that awareness of consequences affects personal norms through one’s responsibilities [
54]. The responsibility aspect is expressed in this study as an attitude of caring for the environment.
4.8. Theoretical Contribution
Based on this study to address the factors that influence the purchase intention of green products, this study concluded that environmental knowledge affected environmental care attitudes. Furthermore, green marketing and environmental care attitudes affected green product purchase intentions.
Figure 3 depicts the final model.
The empirical results of this study address the gap in the prevailing body of literature in reference to the impact of environmental knowledge and green marketing, as well as the effect of environmental care attitudes on product purchase intention. Knowledge does not directly affect intention but is mediated by attitudes that align with the ABC model theory, which mentions that cognition drives attitude behavior [
18]. These findings also support NAM theory which proposes that awareness of responsibilities and consequences reduces the influence of personal norms on behavior because people are aware of their responsibilities and the consequences of their actions [
54]. Therefore, this study applies NAM theory to hypothesize that a person’s attitude towards environmental protection can affect their behavior, one of which is turning to green products, thus making them interested in buying green products. Moreover, this research confirms previous research such as [
6,
7,
8,
19,
20]. Therefore, this study also answered that there is no gap between attitudes and intention, as it has been proven that there is an effect between these two variables. However, WOM is not a driver of attitudes and intentions. For this reason, extensive research is necessary to demonstrate the effect of WOM on green product behavior, as [
3,
4,
5] stated in their studies.
4.9. Policy Implications
According to the study results, Indonesians’ attitudes and purchasing intentions are moderate. Furthermore, environmental knowledge impacts environmental care attitudes, whereas green marketing and environmental care attitudes influence green product purchase intentions. Therefore, consumer environmental knowledge regarding global warming, green products, climate change, greenhouse gas, environmental issues, recycling and waste reduction, green product symbols or signs on product packaging, and green products causing less damage than other products must be improved.
As a result, collaboration with the government, particularly the Ministry of Environment and Forestry (KLHK), companies, and environmental organizations is required to improve the performance of information dissemination with clear, current, and up-to-date information. Environmental issues and eco-labeling are two examples of information that can be disseminated. Furthermore, as stated in Government Regulation of the Republic of Indonesia Number 22 of 2021 concerning the Implementation of Environmental Protection and Management, KLHK can provide education on environmental management and monitoring efforts. Furthermore, institutions that provide access to environmental information are expected to provide examples of activities to preserve the environment and provide adequate facilities to support environmental sustainability, such as facilities providing organic and inorganic waste bins in public places and establishing an organized waste disposal system so that collected organic and inorganic waste does not end up in the landfill. Furthermore, the government can enact policies that promote good waste management, allowing people to embrace environmental stewardship attitudes fully.
Green marketing, in addition to environmental knowledge, influences green purchase intention. As a result, companies are expected to use green marketing to promote their products or services. Green marketing can be accomplished by applying eco-labels to their products and providing information about the environmental impacts of using these green products. As a process, businesses should ramp up their green marketing efforts, such as using environmentally friendly packaging (e.g., paper to reduce plastic); recycling, reusing, and recreating product packaging materials; and conducting product promotions that explain their positive environmental impact. In addition, companies and businesses can use green brand positioning to market their products better and increasing consumers’ purchase intentions for green brands. A successful green brand positioning is seen as an asset for marketers that can use it to differentiate their product from available competitors, create an impression that their product is unique, create more demand and generate more intent to buy more green products.
Based on the results of this study, government or non-government environmental organizations can provide more accurate and up-to-date information to the general public to increase public awareness. For example, companies that sell green products can engage in green marketing that is both honest and appealing to consumers. Subsequently, consumers should share product reviews to increase the reference of other potential consumers before purchasing products.
4.10. Research Limitations
This study is still limited because the researchers used personal social media to distribute online questionnaires, so respondents did not come from all provinces in Indonesia. In addition, samples are not representative of the population or any bias that may have occurred. Furthermore, because only one respondent in this study had a last education below high school, the characteristics of respondents in the last education category were unevenly distributed. Since data collection was performed by non-probability sampling, the findings cannot be generalized to the population level. As a final limitation, the number of respondents was insufficient to represent the entire study area, Indonesia. Morse [
55] stated that for populations larger than 100,000, at least 400 respondents with a margin of error of ±5% are required.
5. Conclusions
According to the results of this study, environmental knowledge, WOM, environmental care attitude, and purchase intention of green products are moderate. This means that people already know enough about the environment, read reviews from others before purchasing certain products, care about the environment, and are very interested in purchasing green products.
The results of hypothesis testing show that three of the seven hypotheses, namely H1, H6 and H7, are accepted, whereas H2, H3, H4, and H5 are rejected. The findings revealed that environmental knowledge significantly impacts environmental care attitudes. Furthermore, green marketing and a caring attitude toward the environment significantly impact green product purchase intention. SEM analysis supports these results, revealing that environmental knowledge significantly affects environmental care attitudes. In contrast, WOM and green marketing do not significantly affect environmental care attitudes. Similarly, environmental knowledge and WOM do not significantly affect green product purchase intention.
Future research may examine other factors influencing attitudes and interest in environmentally friendly products, such as lifestyle, personality, perceived value, culture, green value, functional value, or safety value. Another intriguing research topic is attempting to distinguish consumer living or socio-demographics typology. Finally, future research should aim to extend current research by monitoring actual use rather than intent and examining strategies that can help minimize the green gap.