Preparation of Z-scheme WO3(H2O)0.333/Ag3PO4 composites with enhanced photocatalytic activity and durability

Research Progress of Tungsten Oxide-Based Catalysts in Photocatalytic Reactions

Photocatalysis technology is a potential solution to solve the problem of environmental pollution and energy shortage, but its wide application is limited by the low efficiency of solar energy conversion. As a non-toxic and inexpensive n-type semiconductor, WO3 can absorb approximately 12% of sunlight which is considered one of the most attractive photocatalytic candidates. However, the narrow light absorption range and the high recombination rate of photogenerated electrons and holes restrict the further development of WO3-based catalysts. Herein, the studies on preparation and modification methods such as doping element, regulating defects and constructing heterojunctions to enlarge the range of excitation light to the visible region and slow down the recombination of carriers on WO3-based catalysts so as to improve their photocatalytic performance are reviewed. The mechanism and application of WO3-based catalysts in the dissociation of water, the degradation of organic pollutants, as well as the hydrogen reduction of N2 and CO2 are emphatically investigated and discussed. It is clear that WO3-based catalysts will play a positive role in the field of future photocatalysis. This paper could also provide guidance for the rational design of other metallic oxide (MOx) catalysts for the increasing conversion efficiency of solar energy.

Synergism of carbon quantum dots and Au nanoparticles with Bi2MoO6 for activity enhanced photocatalytic oxidative degradation of phenol

Localized surface plasmon resonance (LSPR) offers an opportunity to enhance the efficiency of photocatalysis. However, the photocatalysts's plasmonic enhancement is still limited, as most metals/semiconductors depend on LSPR contribution of isolated metal nanoparticles. In the present work, carbon quantum dots (CQDs) and Au nanoparticles (NPs) were simultaneously assembled on the surface of a three-dimensional (3D) spherical Bi₂MoO₆ (BMO) nanostructure with surface oxygen vacancies (SOVs). The collective excitation of CQDs and Au NPs demonstrated an effective strategy to improve the utilization of up-conversion emission and plasmonic energy. The contribution of CQDs and Au NPs assembled on the surface of BMO (7 wt% CQDs/Au/BMO) realized a photocatalytic phenol degradation enhancement (apparent rate constants, k _app/min^-1) of 56.5, 9.5 and 3.9, and 2.2-fold increase compared to BMO, BMO-SOVs, Au/BMO and CQDs/BMO, respectively. The as-fabricated 7 wt% CQDs/Au/BMO exhibited the highest mineralization rate for phenol degradation with 72.4% TOC removal rate in 120 min. The excellent photocatalytic performance of CQDs/Au/BMO was attributed to the synergistic effect of CQDs, Au NPs and SOVs. The CQD up-conversion emission synergetically boosts Au NPs' LSPR significantly promoting the separation and migration of photogenerated electron (e^-)/hole (h⁺) pairs, which could improve the oxygen molecule activation process and thereby their ability to generate reactive oxygen species (ROS). The present work is a step forward to understand and construct similar photocatalysts using an entirely reasonable hypothesis of activity enhancement mechanism according to the active species capture experiments and band structure analysis.

Z-scheme polyimide/tungsten trioxide aerogel photocatalyst for enhanced photocatalytic CO2reduction under visible light

Developing highly efficient and stable photocatalysts is an effective method to achieve CO₂photocatalytic reduction. Herein, PI/WO₃aerogel photocatalyst was prepared by chemical amide reaction coupled with an ethanol supercritical drying technique. The novel aerogel photocatalysts exhibit excellent photocatalytic performance for reducing CO₂into CO. In particular, PI/WO₃-10 aerogel photocatalyst shows the highest yield of CO (5.72μmol g^-1h^-1), which is ca 11-fold higher than that of the pristine PI aerogel. The high CO₂reduction activity can be attributed to the Z-scheme structure, which enhances the separation of photo-generated electron-holes, and induces H₂O oxidation on WO₃nanosheets and CO₂reduction on PI aerogel. The photocatalytic reaction mechanism of CO₂when using PI/WO₃aerogel photocatalyst is proposed.

The Multiple Promotion Effects of Ammonium Phosphate-Modified Ag3PO4 on Photocatalytic Performance

Phosphate ( PO 4 3 - ) modification of semiconductor photocatalysts such as TiO₂, C₃N₄, BiVO₄, and etc. has been shown positive effect on the enhancement of photocatalytic performance. In the present study, we demonstrate a novel one-pot surface modification route on Ag₃PO₄ photocatalyst by ammonium phosphate [(NH₄)₃PO₄], which combines PO 4 3 - modification with ammonium ( NH 4 + ) etching to show multiple effects on the structural variation of Ag₃PO₄ samples. The modified Ag₃PO₄ photocatalysts exhibit much higher photocatalytic performance than bare Ag₃PO₄ for the degradation of organic dye solutions under visible light irradiation. It is indicated that the NH 4 + etching favors the surface transition from Ag₃PO₄ to metallic Ag nanoparticles, resulting in the fast capture of photogenerated electrons and the followed generation of O 2 · - radicals. The strongly adsorbed PO 4 3 - on the Ag₃PO₄ surfaces can further provide more negative electrostatic field, which improves the separation of photogenerated electron-hole pairs by inducing the holes to directly flow to the surface and then enhances the formation of reactive ·OH radicals. Furthermore, the photocatalytic performance of the modified Ag₃PO₄ photocatalysts can be optimized by monitoring the concentration of (NH₄)₃PO₄ that is 1 mM.

Facile fabrication of a NiO/Ag3PO4 Z-scheme photocatalyst with enhanced visible-light-driven photocatalytic activity

The photocatalytic performance of Z-scheme NiO/Ag/Ag₃PO₄ was evaluated by degrading organic pollutants under visible light.

Investigation of the kinetics and mechanism of Z-scheme Ag3PO4/WO3 p–n junction photocatalysts with enhanced removal efficiency for RhB

The activity of an Ag₃PO₄/polyhedron-like WO₃ photocatalyst could be enhanced 27 times compared to P25 in the visible light-driven region towards RhB.