Enhanced charge transfer in surface-modified NiTiO3 using high-entropy oxide nanoparticles for solar-driven methanol production

초록

The photocatalytic reduction of CO2 into solar fuels for harnessing solar energy was achieved through the synthesis of a heterostructure comprising a high-entropy oxide (HEO) of (CoCrFeNi)Ox and NiTiO3 nanorods (NTO) prepared by an ammonia evaporation technique. The HEO/NTO heterostructure demonstrated outstanding efficiency in photocatalytic CO2 reduction, as the incorporation of HEO into NTO generated intrinsic electric fields that significantly enhanced charge transfer and suppressed charge carrier recombination. X-ray photoelectron spectroscopy confirmed that HEO acts as a photogenerated electron donor within the HEO/NTO heterostructure. Furthermore, in-situ diffuse reflectance infrared Fourier transform spectroscopy verified the formation of *CH3O and *COOH intermediates, which helped elucidate the kinetic characteristics of the reaction pathway involved in the conversion of CO2 to CH3OH. The optimized HEO/NTO heterojunction exhibited superior photocatalytic CO2 reduction activity, achieving a methanol production rate of 618 mu mol g-1 h-1, which is 9.6 times higher than that of pure NTO. The remarkable enhancement in CO2 reduction was primarily attributed to the efficient transport of photoexcited electrons and holes facilitated by the HEO/NTO heterostructure, as demonstrated by photoluminescence spectra, electrochemical impedance spectroscopy, and transient photocurrent response analyses. Overall, this study presents a promising strategy for the rational design of highperformance heterostructures to improve the transport, separation, and utilization of light-induced charge carriers.

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