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The synergy between an asymmetric Fe–O–Al motif for methane activation and a symmetric Fe–O–Fe motif for oxygen supply enables enhanced methane-to-syngas performance.

Photocatalytic reaction refers to a sophisticated heterogeneous catalyzing process. Exploring the interfacial reaction of catalysts will provide insights into efficient artificial photosynthetic system and promote its design. In this study, highly dispersed bimetallic CuCo2O4 nanoclusters decorated g-C3N4 heterojunction photocatalyst was produced by in-situ deposition of 0D CuCo2O4 spinel on the 2D g-C3N4 surface. Compared with CuO or Co3O4 modified g-C3N4, the optimal composite exhibits a significantly higher H2 evolution rate of 4187.6 μmol∙gcat−1∙h−1 with an apparent quantum yield (AQY) of 4.57% under the irradiation of monochromatic light (400 ± 7.5 nm) in the absence of noble metal. As suggested from the results of the photoelectrochemistry characterizations and NH3-temperature programmed desorption (NH3-TPD) analysis, CuCo2O4/g-C3N4 exhibited faster HER kinetics and considerable surface acidity sites, and it facilitated triethanolamine (TEOA) chemisorption and H2 evolution, further highlighting the merits of such mixed-metal compounds. Moreover, the transfer pathway of charge carriers between CuCo2O4 and g-C3N4 heterogeneous interface was demonstrated by photo-degradation of RhB and selective photo-deposition Pt nanoparticles.

Hydrogen is an important green energy source and chemical raw material for various industrial processes. At present, the major technique of hydrogen production is steam methane reforming (SMR), which suffers from high energy penalties and enormous CO2 emissions. As an alternative, chemical looping water-splitting (CLWS) technology represents an energy-efficient and environmentally friendly method for hydrogen production. The key to CLWS lies in the selection of suitable oxygen carriers (OCs) that hold outstanding sintering resistance, structural reversibility, and capability to release lattice oxygen and deoxygenate the steam for hydrogen generation. Described herein are the recent advances in designing OCs, including simple metal oxides (e.g., Fe, Zn, Ce, and Ti-based metal oxides) and composite metal oxides (e.g., perovskite, spinel, and garnets), for different CLWS processes with emphasis on the crucial parameters that determine their redox performance and future challenges.

It is urgent to seek low-cost and highly efficient cocatalysts for accelerating H2 evolution in photocatalytic water splitting. In this work, bimetallic phosphide NiCoP was synthesized by a simple solvothermal method using red phosphorus as the P source. Then, NiCoP was anchored on the surface of g-C3N4 nanosheets via physical grinding followed calcination. The photocatalytic properties of NiCoP/g-C3N4 were compared in detail with those of monometallic phosphide/g-C3N4 systems (Ni2P/g-C3N4 and Co2P/g-C3N4). The investigation shows that the optimum H2 production rate over NiCoP/g-C3N4 is 5162 μmol g−1 h−1, which is obviously higher than that of the corresponding g-C3N4 (38.5 times), Ni2P/g-C3N4 (1.8 times), Co2P/g-C3N4 (1.6 times) and Pt/g-C3N4 (1.5 times). The apparent quantum yield (AQY) of H2 production over NiCoP/g-C3N4 reaches 18.5% at 400 nm. The superior activity of NiCoP/g-C3N4 is mainly attributed to the synergistic effects of both the excellent charge separation ability due to the Schottky barrier and the lower H2-evolution overpotential compared with the Ni2P or Co2P counterpart. This study further exploits other superior bimetallic phosphides as cocatalysts in the field of solar-to-hydrogen conversion.

Herein, ternary nickel cobalt oxide (NiCo2O4) was firstly employed to increase the photocatalytic water reduction ability of g-C3N4. 17.5 wt%-NiCo2O4/g-C3N4 shows excellent water splitting performance with a H2 production rate of 5480 μmol h−1 g−1, which is extremely better than that of Co3O4, NiO, Pt modified g-C3N4. The quantum efficiency of 17.5 wt%-NiCo2O4/g-C3N4 can reach 4.5% under 400 (±7.5) nm light irradiation. The greatly increased activity of 17.5 wt%-NiCo2O4/g-C3N4 can be attributed to the richer active sites and the superior electrical performance provided by co-existing nickel and cobalt ions with multivalent state. Moreover, the activity of composite almost shows no significant weaken even after 20 h irradiation. A Z-scheme route was put forwarded for H2 production over NiCo2O4/g-C3N4 instead of the traditional p-n junction based on our study.

Constructing high-performance, economical and environmentally friendly photocatalysts remains a challenge for the efficient conversion of solar energy. In this work, CuCo2O4 nanoparticles modified on TiO2 nanosheets have been designed and fabricated via a facile hydrothermal method followed by an in situ calcination process. The resultant 10%-CuCo2O4/TiO2 heterostructure exhibited superior photocatalytic activity under full spectra. The H2 generation rate can reach 4830 μmol g−1 h−1 under 300 W Xe lamp irradiation, which is 32 times higher than that of pristine TiO2 and the highest fold increase of a binary TiO2-based non-noble system reported so far. Its apparent quantum yield (AQY) value can reach 11.5% at 365 nm. Furthermore, we demonstrate that there are chemical bonds formed at the interface between well-dispersed CuCo2O4 and TiO2 by XPS spectrometry and electronegativity theory, and the efficient separation of charge carriers due to the p–n junction adopting the interfacial Ti–O–Cu/Co bonds is crucial for the improved performance and photostability. This work develops possibilities to prepare feasible CuCo2O4-based heterostructures for energy conversion.

Photocatalytic reaction refers to a sophisticated heterogeneous catalyzing process. Exploring the interfacial reaction of catalysts will provide insights into efficient artificial photosynthetic system and promote its design. In this study, highly dispersed bimetallic CuCo