Toward Excellence in Photocathode Engineering for Photoelectrochemical CO₂ Reduction: Design Rationales and Current Progress

Abstract

Photoelectrochemical CO2 reduction reaction (PEC CO2RR) is a promising technology which offers the possibility of a carbon‐neutral solar fuel production via artificial photosynthesis. The challenging proton‐coupled multielectron transfers with high energy barriers in CO2RR however pose as a huge hindrance to the technology, which demands strict specifications in the design of photocathode materials so as to improve PEC performances. This review underscores effective design strategies and current material progress for the judicious assembly of photocathode materials for CO2RR. The review begins with elucidating the fundamental principles of CO2 reduction process and photocathode electrochemistry. Based on these, the design criteria and trade‐offs in the design of PEC CO2RR photocathodes are highlighted. The various promotive strategies for photocathodes and their underlying rationales such as doping, defect engineering, nanostructuring, cocatalyst loading, passivation, heterojunction formation, and innovative multijunction configurations are further outlined and design propositions in the area are provided. Following that, various photocathode semiconductor materials categorized into photovoltaic (PV) grade (silicon, III–V semiconductors, chalcogenides) and non‐PV grade (metal oxides) materials are summarized and extensively discussed, along with their recent advances. Finally, perspectives on the design of photocathodes for CO2RR and new paradigms in the field are put forward.

One-dimensional III-nitrides: towards ultrahigh efficiency, ultrahigh stability artificial photosynthesis

“…Although these challenging requirements have limited the number of semiconductors, careful selection of semiconductors and catalyst materials, and optimization of device structures have realized the CO 2 reduction reaction. [154][155][156][157][158][159][160][161][162][163][164][165][166][167] Recently, 1D nanostructured semiconductor nanowires, nanorods, and nanobers have surpassed the CO 2 reduction reactivity of planar structures due to enhanced light absorption, shortened charge carrier pathways, and exposure of active sites. [168][169][170][171][172][173][174][175] In particular, the emerging 1D III-nitrides have shown great promise for efficient and stable conversion of CO 2 gas into target products.…”

Recyclable, Fire-Resistant, Superstrong, and Reversible Ionic Polyurea-Based Adhesives

“…Carbon dioxide (CO 2 ) is one of the most attractive eco-friendly C1 resources, and its conversion and utilization are receiving global consensus in terms of achieving carbon neutrality and lowering petroleum usage. − Although the inherent thermostability and chemical inertness of CO 2 encumber its upgradation to higher value-added chemicals, numerous endeavors have been devoted to converting CO 2 into hydrocarbon fuels or polymeric materials through developing exquisite catalyst systems, , cooperating with green energies (electricity, solar, or heat), − or coupling with high-energy reactants. − The reduction of CO 2 into hydrocarbon fuels is of paramount importance to alleviate energy and environmental problems, but only a few high-value products are economically viable due to low product selectivity and unsatisfied energy efficiency. − On the other hand, copolymerization of CO 2 with epoxides, diols, diamines, or amino alcohols to synthesize functional polymers [polycarbonate (PC), polyurea (PUa), and polyurethane (PU)] is a highly rewarding CO 2 -valorization approach. − …”

Emerging Single-Atom Catalysts and Nanomaterials for Photoelectrochemical Reduction of Carbon Dioxide to Value-Added Products: A Review of the Current State-of-the-Art and Future Perspectives

“…CO 2 conversion into valuable fuels is scientifically challenging, which is attributed to the high chemical inertness and greater thermodynamic stability of CO 2 , resulting in an appreciable amount of energy that is required for the activation of the CO 2 molecule. , To overcome the thermodynamic barrier, research is progressing on multiple fronts, including catalyst development focusing on modulating the local environment of the PEC electrode to achieve higher selectivity, long-term stability, and better energy efficiency . A distinct class of catalysts that have become one of the emerging fields of research is single-atom catalysts (SACs), owing to their unique coordination environment, low coordination number, and higher atom utilization. − Conventional heterogeneous catalysts usually consist of the wide size distribution of metal species in which only a tiny fraction of metals possessing an appropriate size distribution serve and participate as active catalytic centers, while the rest of the other-size metal species become inert or may initiate undesirable side reactions .…”