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Despite the fact that d‐band center theory links the d electron structure of transition metals to their catalytic activity, it is yet unknown how the synergistic effect of multi‐d electrons impacts catalytic performance. Herein, novel LaNi1‐xCoxRu intermetallics containing 5d, 4d, and 3d electrons were prepared. In these compounds, the 5d orbital of La transfers electrons to the 4d orbital of Ru, which provides adsorption sites for H*. The 3d orbitals of Ni and Co interact with the 5d and 4d orbitals to generate an anisotropic electron distribution, which facilitates the adsorption and desorption of OH*. The synergistic effect of multi‐d electrons ensures efficient catalytic activity. The optimized LaNi0.5Co0.5Ru has an overpotential of 43mV at 10 mA cm−2 for alkaline electrocatalytic hydrogen evolution reaction. Beyond offering a variety of new electrocatalysts, this work reveals the multi‐d electron synergy in promoting catalytic reaction. [ABSTRACT FROM AUTHOR]

The electrocatalytic hydrogen evolution activity of transition metal sulfide heterojunctions are significantly increased when compared with that of a single component, but the mechanism behind the performance enhancement and the preparation of catalysts with specific morphologies still need to be explored. Here, we prepared a Co9S8/MoS2 heterojunction with microsphere morphology consisting of thin nanosheets using a facile two-step method. There is electron transfer between the Co9S8 and MoS2 of the heterojunction, thus realizing the redistribution of charge. After the formation of the heterojunction, the density of states near the Fermi surface increases, the d-band center of the transition metal moves downward, and the adsorption of both water molecules and hydrogen by the catalyst are optimized. As a result, the overpotential of Co9S8/MoS2 is superior to that of most relevant electrocatalysts reported in the literature. This work provides insight into the synergistic mechanisms of heterojunctions and their morphological regulation. [ABSTRACT FROM AUTHOR]

The discovery and identification of novel active sites are paramount for deepening the understanding of the catalytic mechanism and driving the development of remarkable electrocatalysts. Here, we reveal that the genuine active sites for the hydrogen evolution reaction (HER) in LaRuSi are Si sites, not the usually assumed Ru sites. Ru in LaRuSi has a peculiar negative valence state, which leads to strong hydrogen binding to Ru sites. Surprisingly, the Si sites have a Gibbs free energy of hydrogen adsorption that is near zero (0.063 eV). The moderate adsorption of hydrogen on Si sites during the HER process is also validated by in situ Raman analysis. Based on it, LaRuSi exhibits an overpotential of 72 mV at 10 mA cm−2 in alkaline media, which is close to the benchmark of Pt/C. This work sheds light on the recognition of real active sites and the exploration of innovative silicide 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]