Hydrogenated Si-doped g-C3N4: Promising electrocatalyst for CO2 capture and conversion

Abstract

Electrochemically converting CO2 into value-added carbonaceous chemicals offers an effective route to alleviate anthropogenic climate change as well as achieve a carbon–neutral life for society. Herein, a metal-free electrocatalyst of hydrogenated Si-doped C3N4 (HSi1@C3N4) was proposed via the first-principles calculations for carbon dioxide reduction reaction (CO2RR). It was found that the hydrogenation strategy on Si-doped C3N4 remarkably modulated the electronic properties of the Si atom, which accounted for initial CO2 adsorption. In addition, the results demonstrated that the appropriate applied potentials could also boost CO2 activation. Through comprehensive simulations of the reductive reactions under various voltages which have always been studied in experiments, we unravel a cyclic reaction mechanism on –OH terminated HSi1@C3N4 (HSi1@C3N4-OH) for efficient and selective conversion of CO2 into CH4. The effect of Si concentration on CO2 reduction was also studied. The present work predicts the HSi1@C3N4 as high activity and selectivity electrocatalyst towards CO2RR, and highlights the important roles of hydrogenation strategy and applied potentials on CO2 activation, which may provide useful guidance for the design of high-performance and eco-friendly CO2RR electrocatalysts.