Tuning the Electrocatalytic Activity of Pd Nanocatalyst toward Hydrogen Evolution and Carbon Dioxide Reduction Reactions by Nickel Incorporation

Abstract

Electrochemical H₂ generation and CO₂ reduction address the energy and environmental crisis plaguing the world. An efficient electrocatalyst would require the lowest overpotential for these reactions. Given its position on the volcano plot near platinum, palladium presents itself as a viable alternative for the hydrogen evolution reaction (HER). However, the activity is limited by a high overpotential. It is also a good electrocatalyst for the CO₂ reduction reaction (CO₂RR) due to the favorable position of the d-band center. Nevertheless, the CO poisoning of the active site results in low electrocatalytic stability. Herein, we report a Ni-incorporated palladium catalyst, NiPd, which reduces water to H₂ at a very low overpotential of 25 mV (η₁₀). Furthermore, it reduces CO₂ to formate with a very high faradaic efficiency of 97% at a potential of −0.25 V (vs RHE). DFT studies show that Ni inclusion leads to the facile activation of CO₂ due to a bent adsorption configuration at the catalyst surface. The NiPd catalyst exhibits a strong and stable performance for HER (400 h) as well as for CO₂RR (9 h) with high structural integrity as proven by postreaction characterization studies.