Mxene-Derived Ni/Tio2-X/Ti3c2 Catalyst for Enhanced Photothermal Co2 Methanation: Unraveling the Roles of Photoexcited Carriers

Abstract

Photothermal catalysis has emerged as a promising approach for CO2 conversion, which combines photo and thermal energy to drive catalytic reactions efficiently. While light can lower activation barriers and enhance reaction rates, the interplay between light and heat within the catalytic framework remains largely unexplored. In this study, we investigate the critical role of photoexcited carriers in enhancing catalytic performance under solar irradiation, unraveling their contribution to the CO2-to-CH4 conversion process. A multilayer accordion-like Ni/TiO2-x/Ti3C2 catalyst, which exhibits excellent photothermal and photoelectric response characteristics was fabricated for efficient photothermal CO2 methanation. Experimental results demonstrated that introduction of light during thermal catalysis markedly enhanced the CO2 conversion rate, with a 55% increase achieved at 275 ºC. Furthermore, the required temperature for maximum CO2 conversion rate was reduced by 50 ºC compared to the thermal-driven process. Meanwhile, the effects of concentrated ratio and incident wavelength on CO2 conversion were also examined, revealing a synergistic effect between photogenerated carriers and thermal energy. Further characterizations, including steady-state and transient photoluminescence spectroscopy, in-situ XPS, in-situ EPR, in-situ DRITFs, were employed to elucidate the enhancement mechanisms of photogenerated carriers in the catalytic reaction. At the same time, an outdoor experimental prototype was developed to verify the feasibility of photogenerated carrier-thermal synergistically driven CO2 methanation. The findings provide valuable insights into the role of photo-generated carriers in photothermal CO2 methanation, offering new perspectives for the design of efficient photothermal catalysts and advancing solar catalytic CO2 conversion technologies.

Keywords: photothermal catalysis, CO2 methanation, Charge carriers, In-situ experiments, Outdoor prototype