Electron-rich Ni2+ in Ni3S2 boosting electrocatalytic CO2 reduction to formate and syngas

Abstract

Rationally constructed new catalyst can promote carbon dioxide reduction reaction (CO2RR) to valuable carbonaceous fuels such as formate and CO, providing a promising strategy for low CO2 emissions. Herein, the synthesized Ni3S2@C as a highly efficient electro-catalyst exhibits remarkable selectivity for formate with 73.9% faradaic efficiency (FE) at −0.7 V vs. RHE. At high applied potential, it shows a high syngas evolution with CO/H2 ratios (0.54–3.15) that are suitable for typical downstream thermochemical reactions. The experimental and theoretical analyses demonstrate that the electron-rich Ni2+ in Ni3S2 enhances the adsorption behavior of ∗OCHO intermediate, reduces the energy barrier of the formation of intermediates, and improves the selectivity of the formate product. Attenuated total reflection surface-enhanced infrared absorption spectra conducted in situ show that ∗OCHO intermediate is more likely to be generated and adsorbed on Ni3S2, enhancing the selectivity and activity of the formate product.