Hollow TiO2 Microsphere/Graphene Composite Photocatalyst for CO2 Photoreduction

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.

Hollow Nanoreactors for Controlled Photocatalytic Behaviors: Fundamental Theory, Structure–Performance Relationship, and Catalytic Advantages

“…Lo et al compared the photocatalytic activities of TiO 2 HoNRs with cavity sizes ranging from 100 to 400 nm and found that the optimal cavity size for photocatalytic activity was 200 nm. [102] Even, Hsu et al stated that photocatalytic efficiency enhances with the increase in cavity size due to the void effect even after excluding the influence of specific surface area. [48] This difference is also reflected in the range of light absorption, where photocatalysts with larger cavity sizes exhibit smaller bandgaps, indicating a broader light absorption capabilities.…”

“…compared the photocatalytic activities of TiO 2 HoNRs with cavity sizes ranging from 100 to 400 nm and found that the optimal cavity size for photocatalytic activity was 200 nm. [ 102 ] Even, Hsu et al. stated that photocatalytic efficiency enhances with the increase in cavity size due to the void effect even after excluding the influence of specific surface area.…”

Zn-Cr Layered Double Hydroxides for Photocatalytic Transformation of CO2 under Visible Light Irradiation: The Effect of the Metal Ratio and Interlayer Anion

“…Among other detrimental factors, global climate change is largely caused by the increase in atmospheric CO 2 emissions originating from the burning of fossil fuels for energy production, deforestation, and industrial processes. Therefore, the photoreduction of CO 2 (CO 2 PR) in high-added-value products has emerged as an environmental alternative to mitigate the greenhouse effect and energy problems through CO 2 capture and air purification [5][6][7]. Inspired by natural photosynthesis [8], the scientific community has developed many biomimetic approaches to design photocatalytic systems capable of converting CO 2 molecules into valuable fuels (CO, HCHO, HCOOH, CH 3 OH and CH 4 ) under visible light irradiation [9,10].…”

Mixed Metal Oxides of M1 MoVNbTeOx and TiO2 as Composite Catalyst for Oxidative Dehydrogenation of Ethane

“…By the combination of CeO 2 or MnO x with phase-pure M1 catalysts, composite catalysts markedly enhance the catalytic performance for the ODHE process [9,44,45,49], which provides a possibility and preliminary verification on adding cheaper promoters to increase the catalytic activities of MoVNbTeO x catalysts. TiO 2 as an effective promoter/catalyst has been widely used in catalytic processes [50][51][52]. Holmberg et al [53] used TiO 2 as a diluter to study the catalytic performance for propane ammoxidation.…”