CoNi alloy nanoparticles confined by N-doped carbon matrix with tailored d-Band center for electrocatalytic hydrogen evolution

Due to their high intrinsic activity and stability, transition metal-based catalysts are promising candidates for electrocatalytic hydrogen production. Although great effort has been made to enhance the properties of the catalysts, the non-optimized binding energy of hydrogen and the aggregation of the catalysts prohibit the application of transition metal-based catalysts. To solve these problems, the facile d-band center adjustment strategy was designed to prepare CoNi alloy nanoparticles confined by an N-doped carbon matrix. Experimental results demonstrate that the CoNi@NC-500 exhibits high HER activity with an overpotential of 139 mV in 1.0 M KOH. It also exhibits excellent catalytic stability with negligible degradation for 40 h. The improved HER performance of CoNi@NC-500 stems from the N-doped carbon matrix, which could prevent the aggregation of CoNi alloy nanoparticles, thus providing more active sites during HER. Theoretical calculation confirms that the enhanced HER performance is also attributed to the charge transfer between Co and Ni. Therefore, the d-band center of CoNi alloy away from the Fermi level could adjust the adsorption and desorption energy of H, thus optimizing the binding energy of hydrogen intermediates and enhancing the HER performance of the catalyst.