Design of NiCoP nanorod loaded on cocoon carbon substrate and its non-metal doping for efficient hydrogen evolution.

ABSTRACT

The quest for effective and sustainable electrocatalysts for hydrogen evolution is crucial in advancing the widespread use of H2. In this study, we utilized silkworm cocoons as the source material to produce porous N-doped carbon (PNCC) substrates through a process involving degumming and annealing. Subsequently, NiCoP nanorod (NiCoP@PNCC) is deposited onto the substrates via a simple impregnation and calcination method to enhance the catalytic performance for the hydrogen evolution reaction (HER). The optimal spacing between the silk fibers of PNCC facilitates longitudinal growth, increases the active surface area, and balances the adsorption and desorption of reaction intermediates, thereby accelerating HER kinetics. Consequently, NiCoP@PNCC demonstrates impressive performance, with 44 mV overpotential to achieve a current density of 10 mA cm-2. Additionally, density functional theory (DFT) calculations reveal that the electronic structure and energy band of NiCoP@PNCC can be modified through the doping of elements such as B, C, N, O, F, and S. In addition, with the electronegativity enhancement of the doping elements, the interaction between Co atoms in NiCoP@PNCC and O atoms in adsorbed H2O molecules gradually enhanced, which is conducive to the dissociation of water in alkaline solution. This research introduces a novel approach for fine-tuning the catalytic activity of transition metal phosphides.