**2. Literature Review and Hypothesis Development**

#### *2.1. The TPB–ABC Integration Model*

The Theory of Planned Behavior (TPB) proposed by Ajzen et al. in 1991 is a wellestablished theory of the "attitude–behavior" relationship [22]. It has good explanatory and predictive power for the mental decision-making process of goal-oriented behavior. According to TPB, an individual's volitionally controllable behavior results from three internal motivational factors: attitude, subjective norm, and perceived behavioral control [25].

With the development of related research, TPB is considered insufficient to fully explain the complete mechanism of behavior implementation [26]. Since people face various external constraints and limitations when making behavioral decisions, internal motivations are not the only consideration. To improve the research, external contexts have been gradually incorporated into the study of sustainable consumption behavior [27]. The Attitude-Behavior-Context (ABC) theory is the leading theory used to examine the influence of external contexts on sustainable consumption behavior, which states that behavior (Behavior, B) is the result of the joint action of attitude variables (Attitude, A) and contextual factors (Context, C), and considers contextual factors as a crucial factor in determining whether an individual performs the behavior [19]. Many studies confirmed that adding contextual factors can make the model of consumer behavior explanation more complete [28–30].

A growing number of scholars attribute consumer behavior to the combined influence of internal motivations and external contexts, and the TPB–ABC integration model has emerged [31,32]. Wang et al. [33] explored the positive effects of policy instruments, as external contexts, on attitudes and environmental behavior by analyzing the results of a questionnaire survey of 1145 residents in Shanghai. Integrating TPB and ABC theories, Feng and Hua [34] demonstrated that internal motivations and external contexts are essential variables in predicting recycling behavior.

#### *2.2. Sustainable Consumption Behavior (SCB)*

Sustainable consumption refers to a natural, environmentally friendly, frugal, and healthy lifestyle that consumers fulfill under a more ecological and social development premise [35]. From the perspective of behavior, sustainable consumption behavior (SCB) is about the purchase of green products and the choice of green services and includes the use and recycling of products, with the fundamental purpose of protecting resources and the environment [36]. Therefore, SCB can also be seen as a category of personal environmental behavior [37]. In summary, this study defines sustainable consumption behavior as having three sections: green purchase behavior, green transportation behavior and recycling and resource conservation behavior, which correspond to the acquisition, use and disposal of commodities, services, public goods and other means of subsistence by consumers.
