Manipulating the d-band center enhances photoreduction of CO2 to CO in Zn2GeO4 nanorods

Abstract

Enabling catalysts to be highly active for CO2 activation is a crucial priority in photocatalytic CO2 reduction, but extremely challenging. To achieve this, significant electronic modulations based on the atomic-level knowledge of the operational catalytic site are necessary. Herein, a d-band center tuning strategy is proposed to promote the photocatalytic CO2 activation. In a model system taking Zn2GeO4 as photocatalysts, Mn dopants and oxygen vacancies (Vo) were engineered in Zn2GeO4 nanorods (denoted as Mn-ZGO-Vo) to collectively uplift the d-band centers, induced by the ligand and electron redistribution effects. This leads to a strong interaction between the CO2 molecules and Mn-ZGO-Vo, which weakens the C = O bonds for breaking. Temperature-dependent experiments and theoretical calculations reveal that Mn-ZGO-Vo exhibits a low energy barrier of CO2 photoreduction to CO, thereby significantly accelerating the rate-determining step, *COOH formation. Our optimal Mn-ZGO-Vo catalysts, without cocatalyst and sacrificing reagent, demonstrate a high selectivity of 82.9% for photoreducing CO2 to CO, with a CO yield of up to 40.02 μmol g-1h−1, which is nearly 8 times higher compared to pristine Zn2GeO4. Overall, this work not only demonstrates an effective strategy for promoting photocatalytic CO2 adsorption/activation/reduction, but also enriches the application of the d-band tuning concept in the field of photocatalysis.