Developing highly efficient and stable noble-metalfree electrocatalysts for water splitting is critical for producing clean and sustainable energy. Here, we design a hierarchical transition metal hydroxide/sulfide (NiFe(OH) x −Ni 3 S 2 /NF) electrode with dual heterointerface coexistence using a cation exchange-induced surface reconfiguration strategy. The electrode exhibits superior electrocatalytic activities, achieving low overpotentials of 55 mV for hydrogen evolution and 182 mV for oxygen evolution at 10 mA cm −2 . Furthermore, the assembled two-electrode system requires voltages as low as 1.55 and 1.62 V to deliver industrially relevant current densities of 500 and 1000 mA cm −2 , respectively, with excellent durability for over 200 h, which is comparable to commercial electrolysis. Theoretical calculations reveal that the hierarchical heterostructure increases the electronic delocalization of the Fe and Ni catalytic centers, lowering the energy barrier of the rate-limiting step and promoting O 2 desorption. Finally, by implementing the catalysts in a solar-driven water electrolysis system, we demonstrate a record and durable solar-to-hydrogen (STH) conversion efficiency of up to 20.05%. This work provides a promising strategy for developing low-cost and high-efficiency bifunctional catalysts for a large-scale solar-to-hydrogen generation.

The photocatalytic oxidation of benzene to phenol driven by visible light (λ > 420 nm) at room temperature and under ambient pressure is a promising process. In particular, the application of heterogeneous catalysts to benzene photooxidation, where the catalyst and product are easily separated, facilitates the construction of practical processes. Here, we report that a Ptloaded 1D monoclinic WO 3 nanorod (Pt/m-WNR) exhibited higher activities than other Pt/WO 3 catalysts with different crystal structures and morphologies in water under ambient conditions and visible light. Pt/m-WNR showed high stability in repeated reactions. Furthermore, other typical photocatalysts (TiO 2 , Bi 2 WO 6 , Bi 2 MoO 6 , BiOBr, and C 3 N 4 ) showed negligible phenol formation using Pt as a cocatalyst. Both experimental results and density functional theory calculations show that the specific performance of Pt/m-WNR is due to the efficient reduction of O 2 to produce hydroxyl radicals via H 2 O 2 as an intermediate. Notably, m-WNR shows much higher phenol formation than h-WNR, although h-WNR has a higher surface area. The higher activity of m-WNR may be due to its lower work function to provide electrons for O 2 reduction. A lower work function will favorably form a higher Schottky barrier with Pt nanoparticles to suppress the recombination of photogenerated charge carriers. The effect of the Schottky barrier is further confirmed by different activities using various metal particles as cocatalysts.

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The construction of high-efficiency and low-cost non-noble metal bifunctional electrocatalysts for water electrolysis is crucial for commercial large-scale application of hydrogen energy. Here, we report a novel strategy with erbiumdoped NiCoP nanowire arrays in situ grown on conductive nickel foam (Er-NiCoP/NF). Significantly, the developed electrode shows exceptional bifunctional catalytic activity, which only requires overpotentials of 46 and 225 mV to afford a current density of 10 mA cm −2 for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Density functional theory calculations reveal that the appropriate Er incorporation into the NiCoP lattice can significantly modulate the electronic structure with the d-band centers of Ni and Co atoms by shifting to lower energies with respect to the Fermi level, and optimize the Gibbs free energies of HER/OER intermediates, thereby accelerating water-splitting kinetics. When assembled as a solar-driven overall water-splitting electrolyzer, the as-prepared electrode shows a high and stable solar-to-hydrogen efficiency of 19.6%, indicating its potential for practical storage of intermittent energy.