Brookite TiO₂ Nanoparticles Decorated with Ag/MnO_x Dual Cocatalysts for Remarkably Boosted Photocatalytic Performance of the CO₂ Reduction Reaction

Abstract

The solar-driven CO2 reduction reaction (CO2RR) for producing chemical fuels is considered to be a promising approach to dealing with the growing energy crisis and greenhouse effect. Herein, novel Ag/MnO x dual-cocatalyst-decorated brookite titania (BT) nanoparticles with remarkably boosted photocatalytic CO2RR performance are prepared through a facile photodeposition method. The resultant xAg-BT-yMn composite with optimal cocatalyst content delivers amazing CO/CH4 yields of 31.70/129.98 μmol g–1 with an overall photoactivity of 1103.28 μmol g–1 h–1, 11.98 times higher than that of the BT nanoparticles alone. Further investigations demonstrate that the dual cocatalysts decorating the BT nanoparticles not only effectively retard the photoinduced charge recombination but also significantly vary the surface chemical feature to promote the adsorption/activation of the reactants (CO2/H2O). In addition, the Ag nanoparticles can broaden the spectral response region, while the MnO x cocatalyst can promote the CH4 product selectivity and the water oxidation reaction. The synergistic effect of Ag/MnO x dual cocatalysts on the BT nanoparticles renders a remarkably boosted CO2RR performance, which provides a simple yet general synthesis strategy for brookite titania-based photocatalysts with high-performance solar-driven CO2 conversion.

Emerging Strategies for CO2 Photoreduction to CH4: From Experimental to Data‐Driven Design

“…The mechanisms by which the cocatalyst enhances the CH 4 yield and selectivity for photocatalytic CO 2 reduction mainly include the following aspects: 1) The plasmon resonance effect of the metal cocatalyst provides additional hot electrons to participate in the photocatalytic CO 2 reduction process to improve light absorption; [23] 2) The cocatalyst acts as an effective electron absorber in promoting the separation of charge carriers and prolonging the charge lifetime; [119] and 3) The cocatalyst effectively expands the spectral range of the catalyst and improves the light absorption. [125] Overall, we have seen that the development of non-noble metal cocatalysts has been lagging compared to noble metal cocatalysts.…”

“…Meanwhile, MnO x nanoparticles transferred photogenerated holes and catalyze the oxidation of water to produce O 2 , thereby improving O 2 generation activity and CH 4 product selectivity. The synergistic effect between cocatalysts [23,119] and component shows a striking similarity compared to that between defects and component (Section 2.2.2), [93] that is, the rapid separation of charges by inhibiting the recombination together with the enhancement of the surface chemistry involving the adsorption/activation capacity of the reactant (CO 2 /H 2 O), thereby significantly improving the photocatalytic CO 2 RR activity and CH 4 product. The synergistic effect of two noble metal cocatalysts was observed in Janus Pd-Au/TiO 2 heterojunctions.…”

“…We briefly note that the noble metal cocatalysts can also exhibit a synergistic effect with other metal atoms, such as Pd-Au, [28] Ag-Mn, [119] and Pd-Cu, [24] leading to so-called dual-cocatalysts systems. Xiao et al [119] deposited Ag and MnO x nanoparticles on cubic brookite TiO 2 NPs (BT) and investigated its performance for CO 2 photoreduction.…”

“…We briefly note that the noble metal cocatalysts can also exhibit a synergistic effect with other metal atoms, such as Pd-Au, [28] Ag-Mn, [119] and Pd-Cu, [24] leading to so-called dual-cocatalysts systems. Xiao et al [119] deposited Ag and MnO x nanoparticles on cubic brookite TiO 2 NPs (BT) and investigated its performance for CO 2 photoreduction. Each of the dual cocatalysts was found to perform a different role in enhancing photocatalytic activity: Ag nanoparticles played a leading role in promoting charge carrier separation and reduction reactions as an efficient electron sink, hence significantly improving the performance of photocatalytic CO 2 RR.…”

Developing Atomically Thin Li1.81H0.19Ti2O5·2H2O Nanosheets for Selective Photocatalytic CO2 Reduction to CO

“…With the massive consumption of fossil fuels, the excess emission of carbon dioxide (CO 2 ) has caused a huge threat to the ecological environment. − The capture and conversion of CO 2 into useful fuels and chemicals provides a promising sustainable solution to simultaneously alleviate the environmental crisis and reuse the waste gas for the energy shortage. − Since the early trials by Inoue et al to convert CO 2 into carbon-containing small molecules (such as CH 4 , CH 3 OH, HCOOH) on various semiconductor photocatalysts, solar-driven photocatalytic CO 2 reduction to carbon-based fuels has attracted extensive attention. − However, the extremely stable CO bond and the complex multistep reduction process make it challenging to explore efficient photocatalysts for selective CO 2 conversion …”