Development of an efficient catalyst with controlled sulfur vacancies and high pyridine nitrogen content for the photoelectrochemical reduction of CO2 into methanol

To efficiently and selectively produce liquid hydrocarbon fuels, e.g., methanol, by CO2 photoelectrochemical reduction, CdS nanoparticles (NPs) anchored on the nitrogen-doped carbon particles (NCP) with core-shell dodecahedral porous structure were used as cathode catalysts. Electron paramagnetic resonance (EPR) spectra indicated that CdS/NCP treated at 500 degrees C had the maximum S-vacancies. The heterojunction generated between CdS with abundant S-vacancies and NCP with a high content of pyridinic N acted as synergistic catalyst for CO2 reduction. CdS/NCP-500 catalyst exhibited a selectivity of 77.3% towards methanol with a total carbon atom conversion rate of 3052 nmol.h(-1).cm(2). Density functional theory (DFT) calculations revealed that the S-vacancies decreased the energy barrier for CO2 conversion into methanol product. NCP, exhibiting a high adsorption capacity for CO2, allowed the conversion of COOH* into CO* (Delta E = -3.6 eV), which was then transferred to the CdS surface displaying abundant S-vacancies for the reduction into the methanol product. (C) 2019 Elsevier B.V. All rights reserved.