Single-atom catalysts on supported silicomolybdic acid for CO2 electroreduction: a DFT prediction

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) is an effective way to convert CO₂ into fuels which relies on efficient catalysts due to extreme reaction activation barriers. As a new frontier in the field of catalysis, single-atom catalysts (SACs) play an important role in the CO₂RR owing to their maximum atomic availability and unique properties. Herein, a new type of electrocatalyst combining transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag and Cd) with α-Keggin type Na₄[SiMo₁₂O₄₀] (Na₄SiMo₁₂) was investigated by density functional theory (DFT) calculations. Through comprehensive screening, TM@Na₄SiMo₁₂ (TM = Sc, Ti, V, Cr, Mn, Zn, Y, Zr, Nb and Cd) have been found to exhibit robust stability. Among them, TM@Na₄SiMo₁₂ (TM = Sc, Cr, Mn, Ti, and V) have excellent catalytic activity for the CO₂RR; in particular, the limiting potential (U_L) for CO₂RR by Cr@Na₄SiMo₁₂ is −0.23 V and the product is HCOOH. Meanwhile, Mn@Na₄SiMo₁₂ has high CO₂RR selectivity and good catalytic performance (U_L = −0.48 V). During the electrochemical CO₂RR, polyoxometalates (POMs) act as “electron sponges”, accepting and donating electrons. It is expected that the present work will spur the development of new SACs for the CO₂RR.