Search Results (49)

Transition metal dichalcogenides (TMDs) are recognized for their exceptional energy storage capabilities and electrochemical potential, stemming from their unique electronic structures and physicochemical properties. In this study, we focus on chromium disulfide (CrS₂) as the primary research subject and employ a combination of density functional theory (DFT) and first-principle calculations to investigate the effects of incorporating transition metal elements onto the surface of CrS₂. This approach aims to develop a class of bifunctional single-atom catalysts with high efficiency and to analyze their catalytic performance in detail. Theoretical calculations reveal that the Au@CrS₂ single-atom catalyst demonstrates outstanding catalytic activity, with a low overpotential of 0.34 V for the oxygen evolution reaction (OER) and 0.37 V for the oxygen reduction reaction (ORR). These results establish Au@CrS₂ as a highly effective bifunctional catalyst. Moreover, the catalytic performance of Au@CrS₂ surpasses that of traditional commercial catalysts, such as Pt (0.45 V) and IrO₂ (0.56 V), suggesting its potential to replace these materials in fuel cells and other energy applications. This study provides a novel approach to the design and development of advanced transition metal-based catalytic materials. Full article

Atomically dispersed catalysts, including single-atom, dual-atom, and periodic single-metal site catalysts, have revolutionized electrocatalysis by merging atomic precision with heterogeneous stability. This review traces their evolution from pioneering stabilization strategies to advanced microenvironment engineering, enabling breakthroughs in oxygen reduction, hydrogen evolution, and CO₂ reduction. SACs maximize atom utilization but face multi-step reaction limits, addressed by DACs through synergistic dual-site mechanisms. PSMSCs further enhance activity via ordered atomic arrangements, ensuring uniform active sites and mechanistic clarity. Key breakthroughs include microenvironment engineering to tailor active sites, as well as advanced characterization techniques revealing dynamic restructuring under operando conditions. The transition from isolated atoms to ordered ensembles highlights the importance of atomic-level control in unlocking new catalytic mechanisms. This work underscores the transformative potential of ADCs in sustainable energy technologies and provides a roadmap for future research in rational catalyst design, dynamic behavior analysis, and scalable synthesis. Full article

The reasonable design of low-cost, high-activity single-atom catalysts (SACs) is crucial for achieving highly efficient electrochemical CO₂RR. In this study, we systematically explore, using density functional theory (DFT), the performance of transition metal (TM = Mn, Fe, Co, Ni, Cu, Zn)-doped defect-type hexagonal boron nitride (h-BN) SACs TM@B₋₁N (B vacancy) and TM@BN₋₁ (N vacancy) in both CO₂RR and the hydrogen evolution reaction (HER). Integrated crystal orbital Hamiltonian population (ICOHP) analysis reveals that these catalysts weaken the sp orbital hybridization of CO₂, which promotes the formation of radical-state intermediates and significantly reduces the energy barrier for the hydrogenation reaction. Therefore, these theoretical calculations indicate that the Mn, Fe, Co@B₋₁N, and Co@BN₋₁ systems demonstrate excellent CO₂ chemical adsorption properties. In the CO₂RR pathway, Mn@B₋₁N exhibits the lowest limiting potential (U_L = −0.524 V), and its higher d-band center (−0.334 eV), which aligns optimally with the adsorbate orbitals, highlights its excellent catalytic activity. Notably, Co@BN₋₁ exhibits the highest activity in HER, while U_L is −0.217 V. Furthermore, comparative analysis reveals that Mn@B₋₁N shows 16.4 times higher selectivity for CO₂RR than for HER. This study provides a theoretical framework for designing bifunctional SACs with selective reaction pathways. Mn@B₋₁N shows considerable potential for selective CO₂ conversion, while Co@BN₋₁ demonstrates promising prospects for efficient hydrogen production. Full article

The rational design of high-performance catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for the development of clean and renewable energy technologies, particularly in fuel cells and metal-air batteries. Two-dimensional (2D) covalent organic frameworks (COFs) possess numerous hollow sites, which contribute to the stable anchoring of transition metal (TM) atoms and become promising supports for single atom catalysts (SACs). Herein, the OER and ORR catalytic performance of a series of SACs based on TQBQ-COFs were systematically investigated through density functional theory (DFT) calculations, with particular emphasis on the role of the coordination environment in modulating catalytic activity. The results reveal that Rh/TQBQ exhibits the most effective OER catalytic performance, with an overpotential of 0.34 V, while Au/TQBQ demonstrates superior ORR catalytic performance with an overpotential of 0.50 V. A critical mechanistic insight lies in the distinct role of boundary oxygen atoms in TQBQ, which perturb the adsorption energetics of reaction intermediates, thereby circumventing conventional scaling relationships governing OER and ORR pathways. Furthermore, we established the adsorption energy of TM atoms (Ead) as a robust descriptor for predicting catalytic activity, enabling a streamlined screening strategy for SAC design. This study emphasizes the significance of the coordination environment in determining the performance of catalysts and offers a new perspective on the design of novel and effective OER/ORR COFs-based SACs. Full article

The electrochemical carbon dioxide reduction reaction (CO₂RR) represents a promising approach for achieving CO₂ resource utilization. Carbon-based materials featuring single-atom transition metal-nitrogen coordination (M-N_x) have attracted considerable research attention due to their ability to maximize catalytic efficiency while minimizing metal atom usage. However, conventional synthesis methods often encounter challenges with metal particle agglomeration. In this study, we developed a Ni-doped polyvinylidene fluoride (PVDF) fiber membrane via electrospinning, subsequently transformed into a nitrogen-doped three-dimensional self-supporting single-atom Ni catalyst (Ni-N-CF) through controlled carbonization. PVDF was partially defluorinated and crosslinked, and the single carbon chain is changed into a reticulated structure, which ensured that the structure did not collapse during carbonization and effectively solved the problem of runaway M-Nx composite in the high-temperature pyrolysis process. Grounded in X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), nitrogen coordinates with nickel atoms to form a Ni-N structure, which keeps nickel in a low oxidation state, thereby facilitating CO₂RR. When applied to CO₂RR, the Ni-N-CF catalyst demonstrated exceptional CO selectivity with a Faradaic efficiency (FE) of 92%. The unique self-supporting architecture effectively addressed traditional electrode instability issues caused by catalyst detachment. These results indicate that by tuning the local coordination structure of atomically dispersed Ni, the original inert reaction sites can be activated into efficient catalytic centers. This work can provide a new strategy for designing high-performance single-atom catalysts and structurally stable electrodes. Full article

Developing stable and effective catalysts for the hydrogen evolution reaction (HER) has been a long-standing pursuit. In this work, we propose a series of single-atom catalysts (SACs) by importing transition-metal atoms into the carbon and vanadium vacancies of tetragonal V₂C₂ and V₃C₃ slabs, where the transition-metal atoms refer to Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. By means of first-principles computations, the possibility of applying these SACs in HER catalysis was investigated. All the SACs are conductive, which is favorable to charge transfer during HER. The Gibbs free energy change (ΔG_H*) during hydrogen adsorption was adopted to assess their catalytic ability. For the V₂C₂-based SACs with V, Cr, Mn, Fe, Ni, and Cu located at the carbon vacancy, excellent HER catalytic performance was achieved, with a |ΔG_H*| smaller than 0.2 eV. Among the V₃C₃-based SACs, apart from the SAC with Mn located at the carbon vacancy, all the SACs can act as outstanding HER catalysts. According to the ΔG_H*, these excellent V₂C₂- and V₃C₃-based SACs are comparable to the best-known Pt-based HER catalysts. However, it should be noted that the V₂C₂ and V₃C₃ slabs have not been successfully synthesized in the laboratory, leading to a pure investigation without practical application in this work. Full article

Zinc-iodine batteries, which have the advantages of low cost, high safety, long lifespan, and high energy density, currently rank as one of the most promising electrical energy storage devices. However, these batteries still face significant challenges, including sluggish iodine redox kinetics and the shuttle effect of polyiodides. This article provides a comprehensive review of recent advancements in cathode catalysts for zinc-iodine batteries, with a particular focus on the electrochemical processes and working mechanisms of catalysts, and delves into the prospects and scientific issues associated with their development. It then presents a detailed analysis of the mechanisms, principles, and performances of various catalysts, including heteroatom-doped carbon materials, single-atom catalysts, dual-atom catalysts, molecular catalysts, and transition metal compounds, in catalyzing the cathodes of zinc-iodine batteries. These diverse catalysts, with their unique functionalities and catalytic effects, can substantially address the kinetic challenges related to iodine conversion efficiency and the stability issues associated with polyiodide shuttle. Nonetheless, several challenges persist, such as reducing the synthesis cost of catalysts, minimizing catalyst usage to enhance the overall energy density of zinc-iodine batteries, and improving the long-term activity of catalysts. This review is expected to deepen our understanding of cathode catalysts for zinc-iodine batteries and facilitate their practical applications in the future. Full article

This review explores the recent advancements in catalyst technology for hydrogen production, emphasizing the role of catalysts in efficient and sustainable hydrogen generation. This involves a comprehensive analysis of various catalyst materials, including noble metals, transition metals, carbon-based nanomaterials, and metal–organic frameworks, along with their mechanisms and performance outcomes. Major findings reveal that while noble metal catalysts, such as platinum and iridium, exhibit exceptional activity, their high cost and scarcity necessitate the exploration of alternative materials. Transition metal catalysts and single-atom catalysts have emerged as promising substitutes, demonstrating their potential for enhancing catalytic efficiency and stability. These findings underscore the importance of interdisciplinary approaches to catalyst design, which can lead to scalable and economically viable hydrogen production systems. The review concludes that ongoing research should focus on addressing challenges related to catalyst stability, scalability, and the integration of renewable energy sources, paving the way for a sustainable hydrogen economy. By fostering innovation in catalyst development, this work aims to contribute to the transition towards cleaner energy solutions and a more resilient energy future. Full article

Single-atom catalysts (SACs) are presently recognized as cutting-edge heterogeneous catalysts for electrochemical applications because of their nearly 100% utilization of active metal atoms and having well-defined active sites. In this regard, SACs are considered renowned electrocatalysts for electrocatalytic O₂ reduction reaction (ORR), O₂ evolution reaction (OER), H₂ evolution reaction (HER), water splitting, CO₂ reduction reaction (CO₂RR), N₂ reduction reaction (NRR), and NO₃ reduction reaction (NO₃RR). Extensive research has been carried out to strategically design and produce affordable, efficient, and durable SACs for electrocatalysis. Meanwhile, persistent efforts have been conducted to acquire insights into the structural and electronic properties of SACs when stabilized on an adequate matrix for electrocatalytic reactions. We present a thorough and evaluative review that begins with a comprehensive analysis of the various substrates, such as carbon substrate, metal oxide substrate, alloy-based substrate, transition metal dichalcogenides (TMD)-based substrate, MXenes substrate, and MOF substrate, along with their metal-support interaction (MSI), stabilization, and coordination environment (CE), highlighting the notable contribution of support, which influences their electrocatalytic performance. We discuss a variety of synthetic methods, including bottom-up strategies like impregnation, pyrolysis, ion exchange, atomic layer deposition (ALD), and electrochemical deposition, as well as top-down strategies like host-guest, atom trapping, ball milling, chemical vapor deposition (CVD), and abrasion. We also discuss how diverse regulatory strategies, including morphology and vacancy engineering, heteroatom doping, facet engineering, and crystallinity management, affect various electrocatalytic reactions in these supports. Lastly, the pivotal obstacles and opportunities in using SACs for electrocatalytic processes, along with fundamental principles for developing fascinating SACs with outstanding reactivity, selectivity, and stability, have been highlighted. Full article

Rapid industrial growth has overexploited fossil fuels, making hydrogen energy a crucial research area for its high energy and zero carbon emissions. Water electrolysis is a promising method as it is greenhouse gas-free and energy-efficient. However, OER, a slow multi-electron transfer process, is the limiting step. Thus, developing efficient, low-cost, abundant electrocatalysts is vital for large-scale water electrolysis. In this paper, the application and progress of transition metal chalcogenides (TMCs) as catalysts for the oxygen evolution reaction in recent years are comprehensively reviewed. The key findings highlight the catalytic mechanism and performance of TMCs synthesized using single or multiple transition metals. Notably, modifications through recombination, heterogeneous interface engineering, vacancy, and atom doping are found to effectively regulate the electronic structure of metal chalcogenides, increasing the number of active centers and reducing the adsorption energy of reaction intermediates and energy barriers in OER. The paper further discusses the shortcomings and challenges of TMCs as OER catalysts, including low electrical conductivity, limited active sites, and insufficient stability under harsh conditions. Finally, potential research directions for developing new TMC catalysts with enhanced efficiency and stability are proposed. Full article

Developing highly efficient and cost-competitive electrocatalysts for the hydrogen evolution reaction (HER), which can be applied to hydrogen production by water splitting, is of great significance in the future of the zero-carbon economy. Here, by means of first-principles calculations, we have scrutinized the HER catalytic capacity of single-atom catalysts (SACs) by embedding transition-metal atoms in the C and Mo vacancies of a tetragonal Mo₃C₂ slab, where the transition-metal atoms refer to Ti, V, Cr, Mn, Fe, Co, Ni and Cu. All the Mo₃C₂-based SACs exhibit excellent electrical conductivity, which is favorable to charge transfer during HER. An effective descriptor, Gibbs free energy difference (ΔG_H*) of hydrogen adsorption, is adopted to evaluate catalytic ability. Apart from SACs with Cr, Mn and Fe located at C vacancies, all the other SACs can act as excellent catalysts for HER. Full article

The single-atom catalysts (SACs) for the electrocatalytic nitrogen reduction reaction (NRR) have garnered significant attention in recent years. The NRR is regarded as a milder and greener approach to ammonia synthesis. The pursuit of highly efficient and selective electrocatalysts for the NRR continues to garner substantial interest, yet it poses a significant challenge. In this study, we employed density functional theory calculations to investigate the stability and catalytic activity of 29 transition metal atoms loaded on the two-dimensional (2D) AlN monolayer with Al monovacancy (TM@AlN) for the conversion of N₂ to NH₃. After screening the activity and selectivity of NRR, it was found that Os@AlN exhibited the highest activity for NRR with a very low limiting potential of −0.46 V along the distal pathway. The analysis of the related electronic structure, Bader charge, electron localization function, and PDOS revealed the origin of NRR activity from the perspective of energy and electronic properties. The high activity and selectivity towards the NRR of SACs are closely associated with the Os-3N coordination. Our findings have expanded the scope of designing innovative high-efficiency SACs for NRR. Full article

Transition metal (TM) single-atom catalysts (SACs) have been widely applied in photocatalytic CO₂ reduction. In this work, n–p codoping engineering is introduced to account for the modulation of photocatalytic CO₂ reduction on a two-dimensional (2D) bismuth-oxyhalide-based cathode by using first-principles calculation. n–p codoping is established via the Coulomb interactions between the negatively charged TM SACs and the positively charged Cl vacancy (V_Cl) in the dopant–defect pairs. Based on the formation energy of charged defects, neutral dopant–defect pairs for the Fe, Co, and Ni SACs (P_TM⁰) and the −1e charge state of the Cu SAC-based pair (P_Cu⁻¹) are stable. The electrostatic attraction of the n–p codoping strengthens the stability and solubility of TM SACs by neutralizing the oppositely charged V_Cl defect and TM dopant. The n–p codoping stabilizes the electron accumulation around the TM SACs. Accumulated electrons modify the d-orbital alignment and shift the d-band center toward the Fermi level, enhancing the reducing capacity of TM SACs based on the d-band theory. Besides the electrostatic attraction of the n–p codoping, the P_Cu⁻¹ also accumulates additional electrons surrounding Cu SACs and forms a half-occupied d_x²_−y² state, which further upshifts the d-band center and improves photocatalytic CO₂ reduction. The metastability of Cl multivacancies limits the concentration of the n–p pairs with Cl multivacancies (P_TM@nCl (n > 1)). Positively charged centers around the P_TM@nCl (n > 1) hinders the CO₂ reduction by shielding the charge transfer to the CO₂ molecule. Full article

Metal–organic frameworks have demonstrated great capacity in catalytic CO₂ reduction due to their versatile pore structures, diverse active sites, and functionalization capabilities. In this study, a novel electrocatalytic framework for CO₂ reduction was designed and implemented using 2D coordination network-type transition metal–hexahydroxytricyclic quinazoline (TM–HHTQ) materials. Density functional theory calculations were carried out to examine the binding energies between the HHTQ substrate and 10 single TM atoms, ranging from Sc to Zn, which revealed a stable distribution of metal atoms on the HHTQ substrate. The majority of the catalysts exhibited high selectivity for CO₂ reduction, except for the Mn–HHTQ catalysts, which only exhibited selectivity at pH values above 4.183. Specifically, Ti and Cr primarily produced HCOOH, with corresponding 0.606 V and 0.236 V overpotentials. Vanadium produced CH₄ as the main product with an overpotential of 0.675 V, while Fe formed HCHO with an overpotential of 0.342 V. Therefore, V, Cr, Fe, and Ti exhibit promising potential as electrocatalysts for carbon dioxide reduction due to their favorable product selectivity and low overpotential. Cu mainly produces CH₃OH as the primary product, with an overpotential of 0.96 V. Zn primarily produces CO with a relatively high overpotential of 1.046 V. In contrast, catalysts such as Sc, Mn, Ni, and Co, among others, produce multiple products simultaneously at the same rate-limiting step and potential threshold. Full article

The extensive use of single-atom catalysts (SACs) has appeared as a significant area of investigation in contemporary study. The single-atom catalyst, characterized by its maximum atomic proficiency and great discernment of the transition-metal center, has a unique combination of benefits from both heterogeneous and homogeneous catalysts. Consequently, it effectively bridges the gap between these two types of catalysts, leveraging their distinctive features. The utilization of SACs immobilized on graphene substrates has garnered considerable interest, primarily because of their capacity to facilitate selective and efficient photocatalytic processes. This review aims to comprehensively summarize the progress and potential uses of SACs made from graphene in photocatalytic carbon dioxide (CO₂) reduction and hydrogen (H₂) generation. The focus is on their contribution to converting solar energy into chemical energy. The present study represents the various preparation methods and characterization approaches of graphene-based single-atom photocatalyst This review investigates the detailed mechanisms underlying these photocatalytic processes and discusses recent studies that have demonstrated remarkable H₂ production rates through various graphene-based single-atom photocatalysts. Additionally, the pivotal roleof theoretical simulations, likedensity functional theory (DFT), to understand the structural functional relationships of these SACs are discussed. The potential of graphene-based SACs to revolutionize solar-to-chemical energy conversion through photocatalytic CO₂ reduction and H₂ production is underscored, along with addressing challenges and outlining future directions for this developing area of study. By shedding light on the progress and potential of these catalysts, this review contributes to the collective pursuit of sustainable and efficient energy conversion strategies to mitigate the global climate crisis. Full article