In this work, we elucidate real-time mechanistic insights into the promotional
effect of Ni substitution on the bifunctional overall water splitting (OWS)
activity of molybdenum and
tungsten carbides
(Ni-MoC/WC@NGC) supported on N-doped graphitic carbon (NGC). Ni substitution
yields a multi-fold improvement in OWS over the pristine systems, making it
comparable to commercial Pt/C for the hydrogen evolution reaction (HER) and
even outperforming IrO₂ for the oxygen evolution reaction (OER).
Ni-MoC@NGC exhibits remarkable HER activity, with an onset overpotential of 65
mV and a current density of 140 mA/cm² at −370 mV (vs. RHE) in acidic media. A
water electrolyzer constructed with Ni-MoC@NGC demonstrates a comparable cell
voltage to the PtǁIrO₂ pair and can effectively split water using a 1.5V AAA
commercial battery.
First-principles calculations and in-situ probing via quick-XAS during
electrochemical processes provide valuable insights into how the adsorption
energies of intermediates and reaction kinetics are modulated at different
catalytic sites due to the promotional electronic effect of Ni.
Read the full paper here:
https://www.sciencedirect.com/science/article/pii/S092633732100686X#fig0040
