Enhancing d-band center modulation in Carbon-Supported CoP via exogenous nitrogen Dopants: A strategy for boosting Ampere-Level hydrogen evolution reaction

The incorporation of exogenous heteroatoms presents a promising avenue for enhancing the ampere-level hydrogen evolution reaction (HER) by modulating the d-band center of carbon-supported CoP electrocatalysts derived from biomass. In this study, we synthesized carbon-supported CoP electrocatalysts through a simple carbothermal reduction method, using ginkgo leaves as the carbon source. The composition of nitrogen (N) species in the carbon supports was finely tuned by adjusting melamine (MA) addition, optimizing the valence band structure of resulting CoP@N-glC-m (m = 1, 2, 3, 4, and 5) catalysts through electronic metal-support interactions (EMSIs) with CoP nanoparticles (NPs). By correlating the d-band center, work function, N species contents, and η1000 value, we observed a close correlation between the variation of the (pyrrolic N + Co-N)/(pyridinic N + graphitic N) ratio, work function, d-band center, and η1000 value. Notably, CoP@N-glC-3, with the highest ratio of (pyrrolic N + Co-N)/(pyridinic N + graphitic N), exhibited an optimal work function and d-band center, striking a balance between Volmer and Heyrovsky processes, resulting in the highest HER activity among the catalysts. CoP@N-glC-3 demonstrated a 844 mV overpotential, driving the current density to 1000 mA cm−2, more approaching to commercial 20 % Pt/C compared with CoP@glC and CoP@N-glC-m (m = 1, 2, 3 and 5). This research provides crucial insights into electrocatalyst design, connecting chemical properties, valence band structures, and catalytic performance, with profound implications for large-scale HER electrocatalyst production.