Hollow TiO2 Microsphere/Graphene Composite Photocatalyst for CO2 Photoreduction

Yi-Chen Chung,Yi-Wei Lai,Pei-Jie Xie,An-Ya Lo

doi:10.3390/catal11121532

Yi-Chen Chung, Yi-Wei Lai + Show 2 more

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https://doi.org/10.3390/catal11121532

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Journal: Catalysts	Publication Date: Dec 16, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: National Chin-Yi University of Technology

Abstract

In an attempt to improve the photocatalytic activity of anatase TiO2, we developed a composite photocatalyst composed of hollow TiO2 microspheres (hTS) and graphene. The hTS were prepared through a two-step hydrothermal process, where SiO2 microspheres with desirable diameters of 100–400 nm were used as sacrificial templates. Accordingly, the effect of the hTS cavity size on the activity of the catalyst in wet CO2 photoreduction (CO2PR) was studied. Furthermore, it was established that the hydrothermal pH value crucially influences the photocatalytic activity of the hTS photocatalyst, as well as its composition and microstructure. The hTS photocatalyst was also combined with graphene (0–90 wt%) to improve its photocatalytic activity. This study provides insight into the optimal microsphere diameter, hydrothermal pH value, and graphene/hTSx ratio required for designing hollow microsphere-based photocatalysts with enhanced CO2PR performances.

Highlights

Scientists and engineers have been developing diverse green technologies, ranging from CO2 capture to renewable energy and energy conversion devices, to combat the ever-increasing impact of the greenhouse effect and energy crisis on the environment [1,2,3,4,5,6,7,8].CO2 photoreduction (CO2 PR) is the only technology that can consume CO2 to produce valuable fuels using solar energy
The surface morphologies of TS100, TS200, TS300, and TS400 were examined via scanning electron microscopy (SEM) (Figure 1e–h), revealing rougher surfaces than those of their corresponding SS100, SS200, SS300, and SS400 cores
X-ray diffraction (XRD) analyses confirmed the successful coating of the SSx with the desired TiO2 species

Summary

Introduction

Scientists and engineers have been developing diverse green technologies, ranging from CO2 capture to renewable energy and energy conversion devices, to combat the ever-increasing impact of the greenhouse effect and energy crisis on the environment [1,2,3,4,5,6,7,8].CO2 photoreduction (CO2 PR) is the only technology that can consume CO2 to produce valuable fuels using solar energy. Strategies to improve the photocatalytic performance of anatase TiO2 commonly involve incorporating it into various materials or implementing nanoporosity [5,12,14,15]. Some of these methods include heteroatom doping [15,16,17], quantum dot decoration [18], additional semiconductor hybridization [19], and dye sensitization [20]. Graphene is an effective catalyst support that can improve the CO2 PR performance of a catalyst by accelerating electron–hole separation, enhancing CO2 adsorption through π–π conjugation, improving the catalyst specific surface area (SSA), enhancing the catalyst light utilization, and activating CO2 molecules [21,22]

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