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Energy security concerns require novel greener and more sustainable processes, and Paris Agreement goals have put in motion several measures aligned with the 2050 roadmap strategies and net zero emission goals. Renewable energies are a promising alternative to existing infrastructures, with solar energy one of the most appealing due to its use of the overabundant natural source of energy. Photocatalysis as a simple heterogeneous surface catalytic reaction is well placed to enter the realm of scaling up processes for wide scale implementation. Inspired by natural photosynthesis, artificial water splitting's beauty lies in its simplicity, requiring only light, a catalyst, and water. The bottlenecks to producing a high volume of hydrogen are several: Reactors with efficient photonic/mass/heat profiles, multifunctional efficient solar‐driven catalysts, and proliferation of pilot devices. Three case studies, developed in Japan, Spain, and France are showcased to emphasize efforts on a pilot and large‐scale examples. In order for solar‐assisted photocatalytic H2 to mature as a solution, the aforementioned bottlenecks must be overcome for the field to advance its technology readiness level, assess the capital expenditure, and enter the market. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Converting CO2 into valuable C1–C2 chemicals through electrochemical CO2 reduction (ECR) has potential to remedy the ever‐increasing climate problems owing to the intensification of industrial activity. In this work, cradle‐to‐gate life cycle assessment (LCA) was performed to quantify the environmental impacts of formic acid (FA) and ethylene production through ECR benchmarked with the conventional processes. At the midpoint level, global warming potential (GWP) effects of FA and ethylene production through ECR recorded 5.6 and 1.6‐times that of the conventional process, respectively. Although ECR currently has limited environmental benefits, the incorporation of hydropower has vast potential after evaluating four sustainable electricity sources, namely hydropower, wind, solar, and biomass. Notably, ECR to FA recorded a 24 % reduction in petrochemical usage. For ethylene production, human health damage, ecosystem damage, and petrochemical use were reduced by 67, 94, and 110 %, respectively. Sensitivity analysis indicated that a sustainable energy supply chain for ECR will accelerate the development of a circular economy. [ABSTRACT FROM AUTHOR]

Green energy generation is an indispensable task to concurrently resolve fossil fuel depletion and environmental issues to align with the global goals of achieving carbon neutrality. Photocatalysis, a process that transforms solar energy into clean fuels through a photocatalyst, represents a felicitous direction toward sustainability. Eco‐rich metal‐free graphitic carbon nitride (g‐C3N4) is profiled as an attractive photocatalyst due to its fascinating properties, including excellent chemical and thermal stability, moderate band gap, visible light‐active nature, and ease of fabrication. Nonetheless, the shortcomings of g‐C3N4 include fast charge recombination and limited surface‐active sites, which adversely affect photocatalytic reactions. Among the modification strategies, point‐to‐face contact engineering of 2D g‐C3N4 with 0D nanomaterials represents an innovative and promising synergy owing to several intriguing attributes such as the high specific surface area, short effective charge‐transfer pathways, and quantum confinement effects. This review introduces recent advances achieved in experimental and computational studies on the interfacial design of 0D nanostructures on 2D g‐C3N4 in the construction of point‐to‐face heterojunction interfaces. Notably, 0D materials such as metals, metal oxides, metal sulfides, metal selenides, metal phosphides, and nonmetals on g‐C3N4 with different charge‐transfer mechanisms are systematically discussed along with controllable synthesis strategies. The applications of 0D/2D g‐C3N4‐based photocatalysts are focused on solar‐to‐energy conversion via the hydrogen evolution reaction, the CO2 reduction reaction, and the N2 reduction reaction to evaluate the photocatalyst activity and elucidate reaction pathways. Finally, future perspectives for developing high‐efficiency 0D/2D photocatalysts are proposed to explore potential emerging carbon nitride allotropes, large‐scale production, machine learning integration, and multidisciplinary advances for technological breakthroughs. [ABSTRACT FROM AUTHOR]

Sparked by natural photosynthesis, solar photocatalysis using metal‐free graphitic carbon nitride (g‐C3N4) with appealing electronic structure has turned up as the most captivating technique to the quest for sustainable energy generation and pollution‐free environment. Nonetheless, low‐dimensional g‐C3N4 is thwarted from sluggish kinetics and rapid recombination of photogenerated carriers upon light irradiation. Among multifarious modification strategies, engineering 2D cocatalysts is anticipated to accelerate redox kinetics, augment active sites and ameliorate electron–hole separation of 2D g‐C3N4 for boosted activity thanks to its face‐to‐face contact surface. It is of timely and technological significance to review the 2D/2D interfaces with state‐of‐the‐art 2D cocatalysts, spanning from carbon‐containing to phosphorus‐containing, metal dichalcogenide, and other cocatalysts. Fundamental principles for each photocatalytic application will be introduced. Thereafter, the recent advances of 2D/2D cocatalyst‐mediated g‐C3N4 systems will be critically evaluated based on their interfacial engineering, emerging roles, and impacts toward stability and catalytic efficiency. Importantly, mechanistic insights into the charge dynamics and structure–performance relationship will be deciphered. Last, noteworthy research directions are prospected to deliver insightful ideas for future development of g‐C3N4. Overall, this review is anticipated to serve as a scaffold and cornerstone in designing dimensionality‐dependent 2D cocatalyst‐assisted g‐C3N4 toward renewable energy and ecologically green environment. [ABSTRACT FROM AUTHOR]

CO2 capture and conversion has been prospected as an auspicious technology to simultaneously tackle the rise in global CO2 emission and produce value‐added fuels with the goal of accomplishing carbon neutrality. A sustainable route to achieve this is via the utilization of solar energy, thereby harnessing the abundant and nonexhaustive resource to shift our reliance away from rapidly depleting fossil fuels. Graphitic carbon nitride (g‐C3N4) and its allotrope have earned its rank as a fascinating metal‐free photocatalyst due to its superior stability, high surface‐area‐to‐volume ratio, and tunable surface engineering. By leveraging these properties, robust carbon nitride‐based nanostructures are engineered for photocatalytic CO2 conversion to energy‐rich C1C2 product, which is indispensable in the chemical industry. Thus, this review presents the latest panorama of experimental and computational research on tuning the local electronic, surface chemical coordination environment, charge dynamics and optical properties of low‐dimensional carbon nitride and its allotropes toward highly selective and efficient CO2 photoconversion. To name a few, structural engineering, point‐defect engineering, heterojunction construction, and cocatalyst loading. To advance this frontier, critical insights are elucidated to establish the structure‐performance relationship and unravel primary factors dictating the selectivity of C1C2 molecules from CO2 reduction. External‐field assisted photocatalysis such as with electric (photoelectro‐) and heat (photothermal) is discussed to uncover the synergistic contributions that drive the development in photochemistry. Last, future challenges and prospects are outlined for the potential application of solar‐driven CO2 conversion, along with the scale‐up strategy from the economic viewpoint toward the rational development of high‐efficiency carbon nitride catalysts. [ABSTRACT FROM AUTHOR]