Search

g-C3N4 quantum dots (CN QDs)-decorated mesoporous CeO2 composite photocatalyst was prepared by hydrothermal method. The characterized results exhibit that the CN QDs are successfully coupled with mesoporous CeO2, and the photoelectronic response is effectively enhanced. The photocatalytic activity was tested by CO2 reduction, and the results showed that when the loading of CN QDs was 0.75 wt%, the composite photocatalyst has the best photocatalytic activity. After 10 h of UV irradiation, the yields of CO and CH4 were 22.48 µmol/g and 15.81 µmol/g, respectively. Some of the electrons generated within m-CeO2 participated in the CO2 reduction reaction and some were transferred to CN QDs through the two-phase interface to participate in the CO2 catalytic reaction. The oxygen vacancies in m-CeO2 can adsorb CO2 and the introduced CN QDs can excite more oxygen vacancies with m-CeO2 heterostructure, thereby adsorbing more CO2 and photoreduction electrons. [ABSTRACT FROM AUTHOR]

Designing S-scheme heterojunctions is an effective method to improve the charge localization on the surface of photocatalysts. Their effective charge transport routes can be enhanced with the help of interfacial noble metal nanoparticles. Herein, an Ag/CuO@ZnIn 2 S 4 plasma S-scheme heterojunction with heterogeneous interfacial covalent bonds was successfully designed. The 15% Ag/CuO@ZnIn 2 S 4 has promising photocatalytic performance and stability with the highest CO and CH 4 yields of 6.9 and 54.4 µmol g−1 h−1 and CH 4 selectivity of 92.8%. It is evidenced that the photogenerated charge can be efficiently separated and transported due to the influence of both the S-scheme electron migration mode and the Cu-S covalent bond. The process is further accelerated by using precious metals as cocatalysts, which can then selectively convert CO 2 into CH 4. This research is expected to provide helpful information for engineering S-scheme heterojunction photocatalysts and investigating their charge transfer kinetics. [Display omitted] • Design of a S-scheme heterojunction to promote the separation of carriers. • Built the Cu-S bonds to accelerate the transfer of charges. • Utilizing the LSPR effect to generate hot electrons and enhance light absorption. • The Ag/CuO@ZnIn 2 S 4 photocatalysts can selectively reduce CO 2 to CH 4. [ABSTRACT FROM AUTHOR]

• SnS 2 atomic layer with Pt 3 Co nanoclusters have been successfully prepared. • Nanoclusters can enrich electrons, reduce barriers, and promote proton transport. • The photoelectric properties of catalysts is significantly enhanced. • The CO 2 photoreduction efficiency of the SnS 2 /Pt 3 Co catalyst is markedly improved. Poor capability of charge-holes separation and slower surface CO 2 reaction kinetics hinder photocatalytic performance. Here, SnS 2 atomic layer with Pt 3 Co alloy nanoclusters have been successfully prepared. Nanoclusters could be used as highly catalytic active sites, which not only facilitates the carrier separation and transport kinetics, but enriches electrons lowered the reaction barrier. As expected, the CO evolution rate of the champion SnS 2 /Pt 3 Co catalyst was 13.6 times higher than that of the original SnS 2 catalyst under white light irradiation. In-situ DRIFTS identifies key intermediate in the photoreduction process. In-situ XPS and DFT calculation further verifies the electron transport direction and charge density distribution at the SnS 2 /Pt 3 Co interface. Our work uncovers the role of nanoclusters in carrier separation and transport as well as proton transport, opening new chances for obtaining efficient photoreduction CO 2 property. [ABSTRACT FROM AUTHOR]

A series of nebula-like ZnO/CeO 2 @HNTs heterostructure photocatalysts were synthesized via a novel one-step wet-calcination method for degradation of tetracycline (TC) under simulated solar irradiation. TEM, HRTEM, XRD, FT-IR, XPS, DRS, PL, PC, EIS and ESR techniques were applied for characterization of samples. And the potential structure of new photodegradation products was studied by HPLC–MS analysis. The characterization results revealed the enhanced photocatalytic activity of ZnO/CeO 2 @HNTs heterostructure photocatalysts due to the delayed recombination of photogenerated electron-hole pairs. Moreover, surface oxidation state analysis demonstrates that Ce 3+ and Ce 4+ states coexist in CeO 2 , which enhance the separation of electron-hole pairs though cerium oxide shifting between CeO 2 and Ce 2 O 3 under photocatalytic process. In addition, the effects of the calcinating temperature, the molar ratio of ZnO to CeO 2 and the dosage of HNTs on photocatalytic activity of ZnO/CeO 2 @HNTs heterostructure photocatalysts were researched and the best possible values have been found. Furthermore, the photodegradation mechanism was systematically investigated by active species trapping experiment. It revealed that OH radicals play a little role while hole and O 2 − are the more major reactive species in the photodegradation process. [ABSTRACT FROM AUTHOR]

The 15D/R achieve near 99.6% selectivity at the gas–solid interface for UV–Vis light-driven CO 2 reduction to CO, with a rate of 42.41 μmol·g−1. The high conductivity of RGO and the strong interaction with DUT-67 enhanced the electron coupling effect, which was conducive to the separation of carriers. The rapid formation of HCOO− and the rapid desorption of CO are responsible for the high CO yield and selectivity. [Display omitted] • The DUT-67/RGO aerogel are first prepared for CO 2 reduction in a gas–solid system. • 15D/R achieve near 99.6% selectivity for UV–Vis light-driven CO 2 reduction to CO. • Separation efficiency of carriers is the main reason for the improvement of CO yield. Herein, DUT-67/RGO aerogel photocatalysts with three-dimensional (3D) macroscopic morphology were first prepared by a facile hydrothermal and freeze-drying process. It was observed that DUT-67 endowed aerogels with strong adsorption/activation capacity for CO 2 molecules. Besides, RGO not only dispersed DUT-67 as a macroscopic carrier, but also improved the utilization rate of light energy. The high conductivity of RGO and the strong interaction with DUT-67 enhanced the electron coupling effect, which was conducive to the separation of carriers. 15D/R achieved near 99.6% selectivity at the gas–solid interface for UV–Vis light-driven CO 2 reduction to CO, with a rate of 42.41 μmol·g−1. The adsorption behavior of products at the interface and formation process of intermediates were monitored based on CO-TPD and in situ Fourier transform infrared spectra. The extremely high selectivity for CO came from the weak adsorption of CO on the surface of 15D/R and formation of CH 4 required more complex intermediates. [ABSTRACT FROM AUTHOR]

Energy band location and charge separation mechanism of SnS 2 /Au/g-C 3 N 4 system during photoreduction under sunlight irradiation. • The catalyst is prepared by facile thermal treatment and chemical deposition method. • The SnS 2 /Au/g-C 3 N 4 composites show a superior optical adsorption under UV–vis light. • The Au nanoparticle and the Z-type scheme jointly improve the separation of carrier. • The SnS 2 /3ml-Au/g-C 3 N 4 displays the best photoreduction activity and durability. The use of semiconductor photocatalytic reduction technology has higher efficiency and lower energy consumption for CO 2 reduction, but its existence of some mismatched energy band positions and relatively slow charge-hole separation greatly limits its practical application. In this paper, a SnS 2 /Au/g-C 3 N 4 embedded structure model with carbon and nitrogen hybridization is proposed to gain an in-depth understanding of the role of hybridization and precious metal modification in photocatalysis. Carriers were investigated from the perspective of kinetics through photocurrent, LSV curve, and FL spectroscopy. After modification of Au nanoparticles, the photo-excited electrons showed a slower decay process, indicating that the separation of carriers was enhanced, which was further confirmed by impedance and PL spectroscopy. SEM, AFM and TEM analysis confirmed that the 2D face-to-face SnS 2 /Au/g-C 3 N 4 embedded structure was successfully prepared and the Au nanoparticles were evenly distributed. Au nanoparticles not only act as a bridge for electron transport in 2D semiconductor materials to accelerate electron transport, but generate more excited electrons by themselves under the radiation of sunlight, which effectively improves the separation efficiency of electron-hole pairs and enhances the photocatalyst activity. DFT calculations show that the Z-type mechanism and the intercalated energy level of the SnS 2 /Au/g-C 3 N 4 embedded structure expand the light absorption and improve the carrier separation efficiency. As expected, the photocatalyst activity with CO and CH 4 the evolution rate of up 93.81 µmol·g−1·h−1 and 74.98 µmol·g−1·h−1 under visible light irradiation, respectively, while the photocatalytic activity is negligible loss after 30 h photoreduction. This work reveals the role of embedded structure and precious metal modification in the separation and transmission of electron-hole, opening up new perspective for achieving high-efficiency solar CO 2 reduction performance. [ABSTRACT FROM AUTHOR]