A new breakthrough in photocatalytic hydrogen evolution by amorphous and chalcogenide enriched cocatalysts

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. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/cey2.252

Point‐to‐face contact heterojunctions: Interfacial design of 0D nanomaterials on 2D g‐C
 3
 N
 4
 towards photocatalytic energy applications

Recent Advances in g-C3N4-Based Donor–Acceptor Photocatalysts for Photocatalytic Hydrogen Evolution: An Exquisite Molecular Structure Engineering

Having an insight into the optimizations of intrinsic properties of cocatalysts via doping foreign atoms to promote solar-driven water splitting into hydrogen (H2) energy conversion is increasingly important, but it remains a challenging scheme. Herein, zero-dimensional/one-dimensional (0D/1D) structured TMCoSe/CdS0.95Se0.05 was successfully synthesized through a two-pot hydrothermal treatment. Experimental results show that the FeCoSe/CdS0.95Se0.05 photocatalyst exhibits the most excellent photocatalytic H2 evolution performance (513.76 μmol h−1), which is 36.6 times and 2.0 times higher than that of CdS0.95Se0.05 and the optimal CoSe/CdS0.95Se0.05, respectively. In addition, photochemical and photoluminescence results reveal that the FeCoSe/CdS0.95Se0.05 sample shows the most rapid carrier dynamics among all samples. Theoretical calculations demonstrate that the excellent activity of FeCoSe/CdS0.95Se0.05 nanocomposite can be attributed to the formation of Schottky-type heterojunction between semi-metallic FeCoSe cocatalyst and CdS0.95Se0.05, which can enhance the efficiency of charge carrier separation and utilization, thus promoting the H2-generation performance. 

Revealing the effects of transition metal doping on CoSe cocatalyst for enhancing photocatalytic H2 production

Cobalt-Based Cocatalysts for Photocatalytic CO2 Reduction

Recently, semiconductor‐based photocatalytic water splitting has been extensively studied as a promising strategy for converting solar energy into carbon‐neutral and clean H2 fuel. However, the lack of sufficient active sites for surface redox reactions generally results in unsatisfactory photocatalytic water splitting performances over semiconductors. For this problem, cocatalyst provides an encouraging solution and is of great significance in improving photocatalytic performance. Noble metals and their derivatives are mostly utilized as efficient cocatalytic components, but their scarcity and expensiveness severely hamper large‐scale applications. Thereby, the utilization of noble‐metal‐free cocatalysts has aroused immense research attention. Owing to the facile availability, low cost, large abundance, high stability, and efficient performance, transition‐metal‐based materials have been developed as desirable candidates in the photocatalytic water splitting water splitting process. This review gives an outline of some recent advances in the active transition‐metal‐based water splitting cocatalysts. First, the fundamentals of transition‐metal‐based cocatalysts are presented, including the classification, function mechanisms, loading methods, modification strategies, and design considerations. Second, the various cases of depositing reduction cocatalysts, oxidation cocatalysts, and reduction–oxidation dual cocatalysts for water splitting are further discussed. Finally, the crucial challenges and possible research directions of transition‐metal‐based cocatalysts for photocatalytic water splitting are proposed.

Transition‐Metal‐Based Cocatalysts for Photocatalytic Water Splitting

Photocatalytic hydrogen evolution from water vapor presents a novel approach to solar energy conversion. Nevertheless, the design and synthesis of water-adsorbing photocatalysts is exceedingly challenging. In this report, we for the first time present three hygroscopic one-dimensional (1D) covalent organic frameworks (COFs) based on photosensitive pyrene (Py-MPA, Py-PDCA, and Py-HMPA) combined with atmospheric water harvesting (AWH) and photocatalysis for photocatalytic water vapor splitting. Due to the ultra-small pores of the 1D structure, with hydrophilic -OH sites satisfying the microporous filling of water molecules, Py-HMPA demonstrated superior water adsorption capacity at lower humidity. Remarkably, Py-HMPA exhibited an impressive H2 production rate of 105 μmol g−1 h−1 and high stability during solid-state photocatalysis utilizing water vapor. Overall, this work paves a new pathway of organic porous materials for photocatalytic water vapor splitting. 

Wenwen Chi

Papers

Transition‐Metal‐Based Cocatalysts for Photocatalytic Water Splitting

One-dimensional covalent organic frameworks with atmospheric water harvesting for photocatalytic hydrogen evolution from water vapor

Highly Efficient Photocatalytic Production of Hydrogen Peroxide for Ciprofloxacin Degradation by a Cofeo/Pdism Z-Scheme Heterojunction