Optimizing electronic structure of CoSe2 nanorods via N-dopant modulation for superior electrocatalytic hydrogen evolution reaction

Abstract

The hydrogen evolution reaction (HER) performance of transition metal selenides (TMSs) based electrocatalysts in alkaline media is severely affected by numerous issues, including structural instability due to surface oxidation reactions, high overpotentials, and sluggish water dissociation kinetics. Here, we present the simple and scalable synthesis of N-doped cobalt diselenide nanoflowers grown on conductive carbon cloth (N-CoSe2/CC). First, Co(OH)F/CC precursor with a well-defined pore structure through the solvothermal method followed by incorporation of Se ions on the Co mAtrix via a chemical vapor deposition method. Porous CoSe2 was further modified by a heteroatom (N) to enhance electrocatalytic activity, high performance might be attributed to the formation of plentiful active sites, synergistic effects, structural modulation, and improved electronic conductivity. The optimal N-CoSe2/CC catalyst exhibits a high electrochemically active surface area (ECSA) and possesses a low working potential of 73 mV (vs. RHE), which corresponds to 10 mA cm−2 current density, and a lower Tafel slope (75 mV dec−1) in an alkaline medium (1.0 M KOH) with longterm stability of 20 h. The outcomes of the experiment aided by DFT calculations demonstrate that doping of N can significantly alter the electronic states of the “Co” d-orbital, boosting HER performance. This study might open up new possibilities for designing anion-doped transition-metal dichalcogenide electrocatalysts for the potential applicability of HER.