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The fabrication of heterojunctions is an intriguing approach to boost the reactivity of catalysts. However, facile preparation of desirable heterojunction materials remains a challenge. Here, novel CoPS3/CoS2 heterojunctions are created by an intuitive phosphatization process on the basis of structurally flexible cobalt sulfide precursors. Significant stress effect exists at these heterogeneous interfaces, resulting in lattice distortions and the exposure of more active sites. The interface interaction also modifies the catalyst's electronic structure to improve its electrical conductivity and hydrogen adsorption capabilities. Notably, the overpotential of the CoPS3/CoS2 heterojunction for electrocatalytic hydrogen evolution reaction is just 36.3 mV, which is far superior to those of single‐component catalysts and competitive with comparable catalysts reported. This work not only offers an innovative electrocatalyst but also a strategy that can be used to create heterojunctions based on related transition metal thiophosphates. [ABSTRACT FROM AUTHOR]

The separate modulation of the adsorption of *O and *OOH is challenging in oxygen evolution reaction (OER), which results in a large overpotential and slow kinetics. To balance the adsorption of the two active species, here, a way to regulate the local spin state and band structure simultaneously in Ni3S2 nanosheets is reported. The adequate doping of W heteroatoms causes the electron depletion from the Ni active site, which modulates the spin state of eg electrons, weakening the adsorption of *O. Additionally, the introduction of S vacancies contributes to the upshift of the d band center, which strengthens the adsorption of *OOH. In this manner, the adsorption of Ni3S2 for the active intermediates is optimized, resulting in a considerably improved overpotential of 246 mV at 100 mA cm−2 and a Tafel slope of 66 mV dec−1. This work provides insights into the exploration of OER catalysts through synergistic modulation of the spin state and the band structure. [ABSTRACT FROM AUTHOR]

The coordination environment is crucial for the activity of an electrocatalyst, which defines the interaction between the central and adjacent atoms. In traditional 2D MX2 (M = Mo, W, etc., X = S, Se), M is usually coordinated with 6 X atoms in either trigonal prismatic (2H) or octahedral (1T) polyhedrons. With such a coordination configuration, only the edge X sites exhibit activity for hydrogen evolution reaction (HER). Here, a planar‐coordination transition metal chalcogenide, PdSe2 is reported, as an efficient electrocatalyst for the HER in an alkaline electrolyte. By reducing the spatial polyhedron coordination to planar polygon coordination, the M sites in PdSe2 can be efficiently activated to interact with the adsorptive intermediates. As a result, both Pd and Se atoms act as active sites for hydrogen evolution with neutral adsorption ability. With an overpotential of 138 mV at 10 mA cm−2, this work advances the exploration of planar‐coordination HER electrocatalysts. [ABSTRACT FROM AUTHOR]

The surface reconstruction of electrochemically activated catalysts is an effective way to improve performance. However, there is currently a dearth of study on the surface reconstruction of silicide catalysts for hydrogen evolution reactions (HER). Here, a new HER electrocatalyst, LaRuSi3, is synthesized and electrochemically triggered it to produce Ru clusters on its surface. Experimental data and theoretical simulations reveal that Ru clusters optimize the charge distribution of LaRuSi3, which promotes the adsorption of water by Ru sites and improves the adsorption of hydrogen by Si sites. The conductivity and electrochemical active sites of the catalysts are also enhanced. The catalyst has an overpotential of 45 mV to attain a current density of 10 mA cm−2 in alkaline media, which exceeds the majority of other Ru‐based compounds. This work contributes to the exploration of more efficient novel silicides HER electrocatalysts and broadens the application of surface reconstruction techniques. [ABSTRACT FROM AUTHOR]