Defects-Induced Single-Atom Anchoring on Metal-Organic Frameworks for High-Efficiency Photocatalytic Nitrogen Reduction.

Aiming to improve the photocatalytic activity in N2 fixation to produce ammonia, herein, we proposed a photochemical strategy to fabricate defects, and further deposition of Ru single atoms onto UiO-66 (Zr) framework. Electron-metal-support interactions (EMSI) were built between Ru single atoms and the support via a covalently bonding. EMSI were capable of accelerating charge transfer between Ru SAs and UiO-66, which was favorable for highly-efficiently photocatalytic activity. The photocatalytic production rate of ammonia improved from 4.57 µmol g-1 h-1 to 16.28 µmol g-1 h-1 with the fabrication of defects onto UiO-66, and further to 53.28 µmol g-1 h-1 with Ru-single atoms loading. From the DFT results, it was found that d-orbital electrons of Ru were donated to N2 π✶-antibonding orbital, facilitating the activation of the N≡N triple bond. A distal reaction pathway was probably occurred for the photocatalytic N2 reduction to ammonia on Ru1 /d-UiO-66 (single Ru sites decorated onto the nodes of defective UiO-66), and the first step of hydrogenation of N2 was the reaction determination step. This work shed a light on improving the photocatalytic activity via feasibly anchoring single atoms on MOF, and provided more evidences to understand the reaction mechanism in photocatalytic reduction of N2 .

Bismuth-based semiconductors applied in photocatalytic reduction processes: fundamentals, advances and future perspectives.

Bismuth-based semiconductors (BBSs) with their typical layered structures and unique electronic properties are considered an attractive visible light-responsive photocatalysts. Recently, BBS exhibited promising properties and was rapidly developed in photoreduction reactions. In this review, we firstly focus on the photoreduction reactions of BBS with a description of the basic principles. Specifically, the restrictive factors of the photoreduction reactions and the design directions of the catalysts are addressed. BBS photocatalysts, such as bismuth oxide, bismuth halide oxide and bismuth-based oxygenates, are presented in terms of the catalyst material design, crystal structure and other features. Furthermore, the primary applications of BBS in photoreduction reactions are described, including CO2 reduction, N2 reduction, H2 evolution, and nitrate reduction. Additionally, the advances and shortages of BBS applied in these processes are summarized and comprehensively discussed. Future works for BBS applied in photoreduction processes are also proposed.

Recent review of BixMOy (M=V, Mo, W) for photocatalytic CO2 reduction into solar fuels.

The utilization of solar energy for CO2 conversion not only enables a green and low-carbon recycling of CO2 with renewable energy, but also solves ecological problems. BixMOy (M = V, Mo, W) materials have typical layered structures and unique electronic properties that provide suitable band gaps and potential to meet the basic conditions for CO2 reduction. However, pristine BixMOy faces with problems such as small specific surface area, insufficient active sites, low charge carriers' separation and utilization efficiency. This review comprehensively described the basic principles and reaction pathways of photocatalytic CO2 reduction, and further presented the research progress of BixMOy catalysts in CO2 conversion reactions. In this perspective, we further focus on the design concepts and modification strategies to improve the photocatalytic CO2 reduction activity of BixMOy, such as morphology control, constructing surface vacancies and heterojunction fabrication. Finally, based on representative researches, the present review will be expected to provide updated information and insights for developing advanced BixMOy materials to further improve CO2 reduction activity and selectivity.

A novel bismuth hydroxide (Bi(OH)3) semiconductor with highly-efficient photocatalytic activity.

Herein, a novel Bi(OH)3 photocatalyst was successfully synthesized. Benefiting from the suitable band positions, abundant alkaline groups and oxygen vacancies, the as-prepared semiconductor exhibits efficient activity in both photocatalytic CO2 reduction with a CO production rate of 36 µmol g-1 h-1 and phenol decomposition with a 92.7% degradation rate in 180 min.

Photocatalytic Reduction of CO2 on a Bi2MoxW1-xO6 Solid Solution with Enhanced Activity.

This paper reports on a Bi2MoxW1-xO6 solid solution with excellent photocatalytic activity in CO2 reduction. Under simulated sunlight, the Bi2Mo0.25W0.75O6 solid solution achieved a CO generation yield of ≤298.2 µmol g-1 over 3 h, which was 2.1 and 1.5 times larger than those of pristine Bi2WO6 and Bi2MoO6, respectively. Via an in-depth study of the mechanism, this excellent photocatalytic activity was determinied to be probably due to two major contributions: (1) the formation of oxygen vacancies on the Bi2Mo0.25W0.75O6 solid solution, which provided more reactive sites for adsorption and activation of CO2, and (2) modulation of the electronic band structure, which facilitated charge separation. Mechanistic and reaction pathways have been deeply explored and proposed.

Recent Advances of Photocatalytic Application in Water Treatment: A Review.

Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Rapid progress developing novel materials has propelled photocatalysis to the forefront of sustainable wastewater treatments. This review presents the latest progress on applications of photocatalytic wastewater treatment. Our focus is on strategies for improving performance. Challenges and outlooks in this promising field are also discussed. We hope this review will help researchers design low-cost and high-efficiency photocatalysts for water treatment.

Enhanced photocatalytic reduction of CO2 to CO over BiOBr assisted by phenolic resin-based activated carbon spheres.

Photocatalytic reduction of CO2 using solar energy to decrease CO2 emission is a promising clean renewable fuel production technology. Recently, Bi-based semiconductors with excellent photocatalytic activity and carbon-based carriers with large specific surface areas and strong CO2 adsorption capacity have attracted extensive attention. In this study, activated carbon spheres (ACSs) were obtained via carbonization and steam activation of phenolic resin-based carbon spheres at 850 °C synthesized by suspension polymerization. Then, the BiOBr/ACSs sample was successfully prepared via a simple impregnation method. The as-prepared samples were characterized by XRD, SEM, EDX, DRS, PL, EIS, XPS, BET, CO2 adsorption isotherm and CO2-TPD. The BiOBr and BiOBr/ACSs samples exhibited high CO selectivity for photocatalytic CO2 reduction, and BiOBr/ACSs achieved a rather higher photocatalytic activity (23.74 µmol g-1 h-1) than BiOBr (2.39 µmol g-1 h-1) under simulated sunlight irradiation. Moreover, the analysis of the obtained results indicates that in this photocatalyst system, due to their higher micropore surface area and larger micropore volume, ACSs provide enough physical adsorption sites for CO2 adsorption, and the intrinsic structure of ACSs can offer effective electron transfer ability for a fast and efficient separation of photo-induced electron-hole pairs. Finally, a possible enhanced photocatalytic mechanism of BiOBr/ACSs was investigated and proposed. Our findings should provide new and important research ideas for the construction of highly efficient photocatalyst systems for the reduction of CO2 to solar fuels and chemicals.