Directional and Ultrafast Charge Transfer in Oxygen-Vacancy-Rich ZnO@Single-Atom Cobalt Core-Shell Junction for Photo-Fenton-Like Reaction

In photosynthesis, solar energy is harvested by photosensitizers, and then, the excited electrons transfer via a Z-Scheme mode to enzymatic catalytic centers to trigger redox reactions. Herein, we constructed a core–shell Z-scheme heterojunction of semiconductor@single-atom catalysts (SACs). The oxygen-vacancy-rich ZnO core and single-atom Co−N₄ sites supported on nitrogen-rich carbon shell (SA-Co-CN) act as the photosensitizer and the enzyme-mimicking active centers, respectively. Driven by built-in electric field across the heterojunction, photoexcited electrons could rapidly (2 ps) transfer from the n-type ZnO core to the p-type SA-Co-CN shell, finally boosting the catalytic performance of the surface-exposed single-atom Co−N₄ sites for peroxymonosulfate (PMS) activation under light irradiation. The synergies between photocatalysis and heterogeneous Fenton-like reaction lead to phenomenally enhanced production of various reactive oxygen species for rapid degradation of various microcontaminants in water. Experimental and theoretical results validate that the interfacial coupling of SA-Co-CN with ZnO greatly facilitates PMS adsorption and activation by reducing the adsorption energy and enhancing the cascade electron transfer processes for the photo-Fenton-like reaction.     

Efficient Intersystem Crossing and Long-lived Charge-Separated State Induced by Through-Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole-Bodipy Dyad

The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (Φ_Δ=61 %) and long-lived triplet excited state (τ_T=186 μs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (Φ_Δ=0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τ_CSS=24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field.     

Cd/Pt Precursor Solution for Solar H2 Production and in situ Photochemical Synthesis of Pt Single-atom Decorated CdS Nanoparticles

Despite extensive efforts to develop high-performance H₂ evolution catalysts, this remains a major challenge. Here, we demonstrate the use of Cd/Pt precursor solutions for significant photocatalytic H₂ production (154.7 mmol g⁻¹ h⁻¹), removing the need for a pre-synthesized photocatalyst. In addition, we also report simultaneous in situ synthesis of Pt single-atoms anchored CdS nanoparticles (Pt_SA-CdS_IS) during photoirradiation. The highly dispersed in situ incorporation of extensive Pt single atoms on CdS_IS enables the enhancement of active sites and suppresses charge recombination, which results in exceptionally high solar-to-hydrogen conversion efficiency of ≈1 % and an apparent quantum yield of over 91 % (365 nm) for H₂ production. Our work not only provides a promising strategy for maximising H₂ production efficiency but also provides a green process for H₂ production and the synthesis of highly photoactive Pt_SA-CdS_IS nanoparticles.     

Promoting Photocatalytic H2 Evolution through Retarded Charge Trapping and Recombination by Continuously Distributed Defects in Methylammonium Lead Iodide Perovskite

Inspired by its great success in the photovoltaic field, methylammonium lead iodide perovskite (MAPbI₃) has recently been actively explored as photocatalysts in H₂ evolution reactions. However, the practical application of MAPbI₃ photocatalysts remains hampered by the intrinsically fast trapping and recombination of photogenerated charges. Herein, we propose a novel strategy of regulating the distribution of defective areas to promote charge-transfer dynamics of MAPbI₃ photocatalysts. By deliberately designing and synthesizing the MAPbI₃ photocatalysts featuring a unique continuation of defective areas, we demonstrate that such a feature enables retardation of charge trapping and recombination via lengthening the charge-transfer distance. As an outcome, such MAPbI₃ photocatalysts turn out to achieve an impressive photocatalytic H₂ evolution rate as high as 0.64 mmol ⋅ g⁻¹ ⋅ h⁻¹, one order of magnitude higher than that of the conventional MAPbI₃ photocatalysts. This work establishes a new paradigm for controlling charge-transfer dynamics in photocatalysis.     

Boosting Visible-Light Photocatalytic Redox Reaction by Charge Separation in SnO2/ZnSe(N2H4)0.5 Heterojunction Nanocatalysts

In this work, environmentally friendly photocatalysts with attractive catalytic properties are reported that have been prepared by introducing SnO₂ quantum dots (QDs) directly onto ZnSe(N₂H₄)_0.5 substrates to induce advantageous charge separation. The SnO₂/ZnSe(N₂H₄)_0.5 nanocomposites could be easily synthesized through a one-pot hydrothermal process. Owing to the absence of capping ligands, the attached SnO₂ QDs displayed superior photocatalytic properties, generating many exposed reactive surfaces. Moreover, the addition of a specified amount of SnO₂ boosted the visible-light photocatalytic activity; however, the presence of excess SnO₂ QDs in the substrate resulted in aggregation and deteriorated the performance. The spectroscopic data revealed that the SnO₂ QDs act as a photocatalytic mediator and enhance the charge separation within the type II band alignment system of the SnO₂/ZnSe(N₂H₄)_0.5 heterojunction photocatalysts. The separated charges in the heterojunction nanocomposites promote radical generation and react with pollutants, resulting in enhanced photocatalytic performance.     

Thiophene-Containing Covalent Organic Frameworks for Overall Photocatalytic H2O2 Synthesis in Water and Seawater

H₂O₂ is a significant chemical widely utilized in the environmental and industrial fields, with growing global demand. Without sacrificial agents, simultaneous photocatalyzed H₂O₂ synthesis through the oxygen reduction reaction (ORR) and water oxidation reaction (WOR) dual channels from seawater is green and sustainable but still challenging. Herein, two novel thiophene-containing covalent organic frameworks (TD-COF and TT-COF) were first constructed and served as catalysts for H₂O₂ synthesis via indirect 2e⁻ ORR and direct 2e⁻ WOR channels. The photocatalytic H₂O₂ production performance can be regulated by adjusting the N-heterocycle modules (pyridine and triazine) in COFs. Notably, with no sacrificial agents, just using air and water as raw materials, TD-COF exhibited high H₂O₂ production yields of 4060 μmol h⁻¹ g⁻¹ and 3364 μmol h⁻¹ g⁻¹ in deionized water and natural seawater, respectively. Further computational mechanism studies revealed that the thiophene was the primary photoreduction unit for ORR, while the benzene ring (linked to the thiophene by the imine bond) was the central photooxidation unit for WOR. The current work exploits thiophene-containing COFs for overall photocatalytic H₂O₂ synthesis via ORR and WOR dual channels and provides fresh insight into creating innovative catalysts for photocatalyzing H₂O₂ synthesis.     

水热法制备NiS/Cd1-xZnxS及其高效光催化产氢性能

利用水热法制备 NiS 负载的 Cd1-xZnxS 光催化剂.结果表明：在0.35 mol?L-1 Na2SO3和0.25 mol?L-1 Na2S牺牲剂下,0.5%(摩尔分数, y) NiS/Cd0.3Zn0.7S (1840μmol?h-1)获得最好活性,是Cd0.3Zn0.7S (884μmol?h-1)的2.1倍,高于0.5%(质量分数, w) Pt (1390μmol?h-1)的产氢活性.测得其在λ=420 nm附近的表观量子效率为36.8%. X射线衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、透射电子显微镜(TEM)以及X射线光电子能谱(XPS)的表征结果表明, NiS作为产氢活性位,转移光生电子,因此提高了光催化产氢活性.