Photoelectrocatalytic reduction of CO2 to syngas over Ag nanoparticle modified p-Si nanowire arrays

Abstract

The solar energy-driven reduction of CO₂ and H₂O to syngas (H₂/CO), an important platform to produce chemicals, is of significance for alleviating greenhouse gas emission and utilizing sustainable solar energy. Here, we report a facile method for the photoelectrocatalytic reduction of CO₂ and H₂O to syngas over an Ag nanoparticle (NP) modified p-Si nanowire array catalyst. The particle size of Ag significantly influences the activity of CO₂ reduction to CO. The H₂/CO molar ratio in reduction products can be tuned in the range from 1 to 4 by controlling the size of Ag NPs from 4.2 to 16 nm. The adsorption strength of CO on the catalyst was found to decline with the increase in the size of Ag NPs. The Ag NPs of 8.2 nm, which possess a moderate CO adsorption strength, exhibit the maximum production of CO with the H₂/CO ratio of 2/1.