Ruthenium-based catalysts face significant challenges of electrochemical dissolution and slow reaction kinetics for the oxygen evolution reaction (OER). Here, we have shown the enhancement of the activity and stability of Ru doped on a binary Ni-Mo₂N support with three-dimensional (3D) filamentous network structure (Ru/Ni-Mo₂N) for OER. X-ray photoelectron spectroscopy (XPS) reveals the increase of the electron density around Ru sites by the interaction with Ni-Mo₂N. Density functional theory (DFT) calculations confirm that this interaction induces a downshift of the d-band center of Ru sites, leading to optimized adsorption energies of intermediates on Ru and enhanced OER performance. Moreover, the sacrificial behavior of Ni effectively mitigates Ru over-oxidation and dissolution, thereby enhancing OER stability. Also, the 3D filamentous network structure with abundant pores is favorable to accelerate the transfer of electrolyte. As a result, the Ru/Ni-Mo₂N requires an overpotential of 251 mV to achieve 20 mA·cm⁻², being 83 mV lower than that of Ru-Mo₂N. An anion exchange membrane water electrolyzer (AEMWE) (Pt/C||Ru/Ni-Mo₂N) delivers a voltage of 1.78 V at 500 mA·cm⁻², superior to that of the Pt/C||RuO₂ (1.97 V@500 mA·cm⁻²), and exhibits stable operation for over 500 h. This study demonstrates the critical role of the binary support in enhancing the catalytic activity and stability of Ru-based catalysts.

Replacing the challenging water oxidation with thermodynamically favorable organic oxidation presents a promising strategy for the efficient simultaneous production of hydrogen and value-added chemicals. However, photocatalytic activity is hindered by inefficient separation of photogenerated electron–hole pairs and limited redox active sites. Herein, Fe/ZnIn₂S₄/Ni (Fe/ZIS/Ni) micro heterojunctions were rationally engineered for synergistically photocatalytic hydrogen evolution and selective oxidation of benzylamine. Using Fe-based metal–organic frameworks (MIL-88A) as the self-etching morphology template and iron source, ZIS was grown in situ to obtain Fe-doped ZIS (Fe/ZIS). Then nickel was introduced into Fe/ZIS to locally construct Ni-doped ZIS (ZIS/Ni) microregion, thereby forming numerous microscopic heterojunctions (Fe/ZIS/Ni). The introduction of Fe effectively lowers the energy band (EB) position of Fe/ZIS, while the introduction of Ni elevates the EB position of ZIS/Ni microregion. Such difference in the EB structures of Fe/ZIS and ZIS/Ni promote the formation of local electric field, effectively suppresses the recombination of photogenerated carriers and enhances their efficient separation and migration. Moreover, the nanosheet assembly structure increases the availability of active sites and enhances the uptake of reactants. The optimized Fe/ZIS/Ni catalyst achieves remarkable hydrogen evolution and N-benzylidenebenzylamine (NBI) production rates of 7.9 and 6.8 mmol·g⁻¹·h⁻¹, respectively. Additionally, the selectivity for the oxidation of benzylamine to NBI exceeds 95%. This work establishes a novel design paradigm for developing high-performance photocatalytic systems that integrate renewable H₂ production with selective organic transformations.

Developing highly-efficient bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts is crucial for the widespread application of rechargeable Zn–air batteries (ZABs). Herein, an efficiency electrodeposition and pyrolytic strategy to synthesize the three-dimensional (3D) N-doped carbon coating multiple valence Co and MnO heterostructures supported on carbon cloth substrate (Co-MnO@NC/CC). It contains Co–Co, Co–N, and Co–O bonds, which synergistically enhance the oxygen reaction activity with MnO. It exhibits a working potential of 1.473 V at 10 mA·cm⁻² for OER and onset potential of 0.97 V for ORR. Theory calculations demonstrate that the synergy between cobalt and manganese species could optimize the d-band center and reduce the energy barrier of Co-MnO@NC/CC for both OER and ORR processes. Besides, the MnO acts as the main OER active site could significantly optimize the energy barrier of O* → OOH*, thus further promoting the OER activity. It can be directly used as the air-cathode for both liquid-state and solid-state ZABs, which could afford a small voltage gap of 0.75 V at 10 mA·cm⁻², a high power density of 172.5 mW·cm⁻² and a long-term durability for 400 h, surpassing those of the Pt/C + RuO₂-based ZAB. Importantly, the assembled batteries show potential applications in portable devices.

Electrocatalytic water splitting is an essential and effective means to produce green hydrogen energy structures, so it is necessary to develop non-precious metal catalysts to replace precious metals. Cobalt-based catalysts present effective alternatives due to the diverse valence states, adjustable electronic structures, and plentiful components. In this review, the catalytic mechanisms of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for electrocatalytic water splitting are described. Then, the synthesis strategies of various cobalt-based catalysts are systematically summarized, followed by the relationships between the structure and performance clarified. Subsequently, the effects of d-band center and spin regulation for cobalt-based catalysts are also discussed. Furthermore, the dynamic electronic and structural devolution of cobalt-based catalysts are elucidated by combining a series of in-situ characterizations. Finally, we highlight the challenges and future developed directions of cobalt-based catalysts for electrocatalytic water splitting.

Given the grim situation of global warming and energy crisis, replacing traditional energy conversions based on carbon cycle with water cycle is a sustainable development trend. The synergistic electrocatalysis for value-added chemical production through oxygen species (O_ads: OH*, O*, and OOH*) and the active hydrogen species (H_ads) derived from water splitting powered by “green” electricity from renewable energy resource (wind, solar, etc.) is a promising manner, because of its reduced energy consumption and emission and high Faradaic efficiency. The study and summarization of catalytic mechanism of synergistic electrocatalysis are particularly significant, but are rarely involved. In this review, recent progress of various synergistic electrocatalysis systems for generating valuable products based on water cycle is systematically summarized. Importantly, the catalytic mechanism of synergistic electrocatalysis and the positive effect of O_ads and H_ads species produced by water splitting during the synergistic electrocatalytsis are detailedly elucidated. Furthermore, the regulation of water-derived O_ads and H_ads species for achieving efficient matchability of synergistic electrocatalysis is emphatically discussed. Finally, we propose the limitations and future goals of this synergistic system based on water cycle. This review is guidance for design of synergistic electrocatalysis architectures for producing valuable substances based on water cycle.

The Pt-free photocatalytic hydrogen evolution (PHE) has been the focus in the photocatalytic field. The catalytic system with the large accessible surface and good mass-transfer ability, as well as the intimate combination of co-catalyst with semiconductor is promising for the promotion of the application. Here, we have reported the design of the two-dimensional (2D) porous C₃N₄ nanosheets (PCN NS) intimately combined with few-layered MoS₂ for the high-effective Pt-free PHE. The PCN NS were synthesized based on peeling the melamine–cyanuric acid precursor (MC precursor) by the triphenylphosphine (TP) molecular followed by the calcination, mainly due to the matched size of the (100) plane distance of the precursor (0.8 nm) and the height of TP molecular. The porous structure is favorable for the mass-transfer and the 2D structure having large accessible surface, both of which are positive to promote the photocatalytic ability. The few-layered MoS₂ are grown on PCN to give 2D MoS₂/PCN composites based on anchoring phosphomolybdic acid (PMo₁₂) cluster on polyetherimide (PEI)-modified PCN followed by the vulcanization. The few-layered MoS₂ have abundant edge active sites, and its intimate combination with porous PCN NS is favorable for the faster transfer and separation of the electrons. The characterization together with the advantage of 2D porous structure can largely promote the photocatalytic ability. The MoS₂/PCN showed good PHE activity with the high hydrogen production activity of 4,270.8 μmol·h⁻¹·g⁻¹ under the simulated sunlight condition (AM1.5), which was 7.9 times of the corresponding MoS₂/bulk C₃N₄ and 12.7 times of the 1 wt.% Pt/bulk C₃N₄. The study is potentially meaningful for the synthesis of PCN-based catalytic systems.

Hydrodesulfurization (HDS) is an essential process in clean fuel oil production, however, the huge challenge is the synthesis of the catalyst with plentiful active sites. Here, we have shown the design of few-layered, ultrashort Ni-Mo-S slabs dispersed on reduced graphene oxide (Ni-Mo-S/rGO-A) based on anchoring [PMo₁₂O₄₀]³⁻ clusters and Ni²⁺ on polyethyleneimine (PEI)-modified graphite oxide. Structural characterizations (transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), etc.) show that Ni-Mo-S slabs with predominant monolayer and partial substitution of edge Mo atoms by isolated Ni atoms have rich accessible edge Ni-Mo-S sites and high sulfurization degree. All virtues endow it with plentiful edge-active sites, and consequently, the enhanced performance for hydrodesulfurization of dibenzothiophene (DBT). The hydrodesulfurization proceeds via a more-favorable direct desulfurization (DDS) route with a reaction rate constant (k_HDS) of 48.6 × 10⁻⁷ mol·g⁻¹·s⁻¹ over Ni-Mo-S/rGO-A catalyst, which is 4.3 times greater than that over traditional Ni-Mo-S/Al₂O₃ catalyst and at the forefront of reported catalysts.