High-Dispersive Pd Nanoparticles on Hierarchical N-Doped Carbon Nanocages to Boost Electrochemical CO2 Reduction to Formate at Low Potential

Abstract

Electrochemical CO₂ reduction reaction (CO₂ RR) to value-added chemicals/fuels is an effective strategy to achieve the carbon neutral. Palladium is the only metal to selectively produce formate via CO₂ RR at near-zero potentials. To reduce cost and improve activity, the high-dispersive Pd nanoparticles on hierarchical N-doped carbon nanocages (Pd/hNCNCs) are constructed by regulating pH in microwave-assisted ethylene glycol reduction. The optimal catalyst exhibits high formate Faradaic efficiency of >95% within -0.05-0.30 V and delivers an ultrahigh formate partial current density of 10.3 mA cm^-2 at the low potential of -0.25 V. The high performance of Pd/hNCNCs is attributed to the small size of uniform Pd nanoparticles, the optimized intermediates adsorption/desorption on modified Pd by N-doped support, and the promoted mass/charge transfer kinetics arising from the hierarchical structure of hNCNCs. This study sheds light on the rational design of high-efficient electrocatalysts for advanced energy conversion.

Keywords: electrochemical CO 2 reduction reaction; formate; hierarchical N-doped carbon nanocages; palladium; size regulation.