Nanostructure rod-like TiO2-reduced graphene oxide composite aerogels for highly-efficient visible-light photocatalytic CO2 reduction

Abstract

In response to the worldwide over-standard carbon dioxide emission problem, this work synthesized a series of titanium dioxide/reduced graphene oxide composite aerogels (TiO2-rGO) for photoconversion of CO2 by a one-step hydrothermal and freeze-drying method. The prepared composite aerogel presents a high specific surface area of 287.3 m2/g and pore volume of 0.72 cm3/g, contributing to remarkable absorption capability of reactants and fast intraparticle molecular transfer. In the three-dimensional structure of rGO aerogel, TiO2 with nano-rod shape (10–20 nm × 100–150 nm) is uniformly interspersed. Through applying the composite catalytic aerogel for the photocatalysis reaction, CO2 was efficiently converted to MeOH, CH4, and EtOH, etc. The total yield of carbon generated by G-25Ti (TiO2-rGO with 25 mmol Ti4+) was found 15.7 times higher than that of the pure P25. The corresponding characteristic analysis demonstrated that the photocatalytic performance of TiO2-rGO composite aerogel has been highly improved, originated from two folds: (1) the introduction of 3-D rGO to nano-rod shape TiO2 promoted its light absorption efficiency, and more significantly (2) the specific chemical bonding sites and strong O˭C‒O‒Ti group between rGO and TiO2 effectively mitigate the recombination of photogenerated electron–hole pairs. In this work, rod-like TiO2-rGO composite aerogels prepared by using TiCl4 as precursor for the first time have been found a new application in CO2 reduction using visible sunlight.