Hydrazine-modified Zn-oxysulfide nanoparticles for CO2 reduction under low UV-light illumination

Abstract

Photo-catalytically hydrogen-evolved Zn(O,S) nanoparticles (NPs) have been prepared with different amounts of hydrazine (0, 0.25, 0.5, 0.75, 1, 2 mL) to induce more oxygen vacancy sites on catalyst surfaces and utilized to reduce CO2 with different hole scavenger reagents. The as-prepared catalysts with different hydrazine amounts were first examined with XRD diffractometer, FE-SEM, and electrochemical impedance spectroscopy (EIS). The EIS spectroscopy indicated Zn(O,S) NPs with 0.75 mL hydrazine had the most efficient electron transfer property, therefore it was further used for photocatalytic CO2 reduction experiment. Some hole scavenger reagents such as Na2SO4, ozon, ethanolamine, H3PO4, and H2O2 were used in this experiment. It was observed that hydrazine and hole scavengers played a critical role to enhance CO2 reduction. The highest amount of CO2-converted ethanol was achieved with 0.75 mL-hydrazine-modified Zn(O,S) using Na2SO4 and ozon simultaneously as hole scavenger reagents. The proposed mechanism which involved generated oxygen vacancy sites during the photocatalytic session was elucidated with Kröger-Vink notation.