Extraordinary Changes in the Electronic Structure and Properties of CdS and ZnS by Anionic Substitution: Cosubstitution of P and Cl in Place of S

Unlike cation substitution, anion substitution in inorganic materials such as metal oxides and sulfides would be expected to bring about major changes in the electronic structure and properties. In order to explore this important aspect, we have carried out first‐principles DFT calculations to determine the effects of substitution of P and Cl on the properties of CdS and ZnS in hexagonal and cubic structures and show that a sub‐band of the trivalent phosphorus with strong bonding with the cation appears in the gap just above the valence band, causing a reduction in the gap and enhancement of dielectric properties. Experimentally, it has been possible to substitute P and Cl in hexagonal CdS and ZnS. The doping reduces the band gap significantly as predicted by theory. A similar decrease in the band gap is observed in N and F co‐substituted in cubic ZnS. Such anionic substitution helps to improve hydrogen evolution from CdS semiconductor structures and may give rise to other applications as well.     

Room‐Temperature Decarboxylative Alkynylation of Carboxylic Acids Using Photoredox Catalysis and EBX Reagents

Alkynes are used as building blocks in synthetic and medicinal chemistry, chemical biology, and materials science. Therefore, efficient methods for their synthesis are the subject of intensive research. Herein, we report the direct synthesis of alkynes from readily available carboxylic acids at room temperature under visible‐light irradiation. The combination of an iridium photocatalyst with ethynylbenziodoxolone (EBX) reagents allowed the decarboxylative alkynylation of carboxylic acids in good yields under mild conditions. The method could be applied to silyl‐, aryl‐, and alkyl‐ substituted alkynes. It was particularly successful in the case of α‐amino and α‐oxo acids derived from biomass.     

Increased Water Reduction Efficiency of Polyelectrolyte‐Bound Trimetallic [Ru,Rh,Ru] Photocatalysts in Air‐Saturated Aqueous Solutions

The groundbreaking use of polyelectrolytes to increase the efficiency of supramolecular photocatalysts in solar H₂ production schemes under aqueous aerobic conditions is reported. Supramolecular photocatalysts of the architecture [{(TL)₂Ru(BL)}₂RhX₂]⁵⁺ (BL=bridging ligand, TL=terminal ligand, X=halide) demonstrate high efficiencies in deoxygenated organic solvents but do not function in air‐saturated aqueous solution because of the quenching of the metal‐to‐ligand charge‐transfer (MLCT) excited state under these conditions. The new photocatalytic system incorporates poly(4‐styrenesulfonate) (PSS) into aqueous solutions containing [{(bpy)₂Ru(dpp)}₂RhCl₂]⁵⁺ (bpy=2,2′‐bipyridine, dpp=2,3‐bis(2‐pyridyl)pyrazine). PSS has a profound impact on the photocatalyst efficiency, increasing H₂ production over three times that of deoxygenated aqueous solutions alone. H₂ photocatalysis proceeds even under aerobic conditions for PSS‐containing solutions, an exciting consequence for solar hydrogen‐production research.     

基于可调控多肽纳米管和石墨烯复合纳米结构的光吸收催化平台

近年来, 自组装纳米结构因为其容易制备、稳定、环保以及与各种功能基团、粒子等的多样结合能力吸引了科学家们的目光, 成为人们研究的热点课题, 在光电池、光催化、水凝胶、药物缓释等方面的实验科学领域得到了广泛的应用. 尤其是光催化方面, 自组装结构的重复性为激子的传递创造了比较良好的条件, 成为众多激子传递平台中的佼佼者. 本文报道了一种以苯丙氨酸二肽纳米管和羧基石墨烯为基础的自组装光吸收催化平台, 对其结构进行研究, 并使用该体系进行了烟酰胺腺嘌呤二核苷酸到它的还原态的催化实验. 该体系的微观结构由纳米管和石墨烯膜复合而成, 羧基石墨烯的存在能够降低纳米管直径, 实现纳米管的形态操控, 石墨烯与多肽纳米管复合纳米结构的存在实现了多通道协同激子传递, 降低了激子传递的距离, 极大增强了催化中心对于激子的接受和使用效率. 在复合了光敏剂和催化中心之后, 该体系具有较高的稳定性, 均一的分散性, 很强的光能吸收和转化能力等性质. 对于从NADP⁺往NADPH转变的催化实验表明, 该体系有较高的反应速率和催化效率, 并且比两种单一结构催化平台效果之和更好, 实现了一加一大于二的效应, 展现了复合纳米结构光吸收催化平台的巨大潜力和广阔应用前景.     

Photocatalytic Oxidation of HMF under Solar Irradiation: Coupling of Microemulsion and Lyophilization to Obtain Innovative TiO2-Based Materials

The photocatalytic oxidation of biomass-derived building blocks such as 5-hydroxymethylfurfural (HMF) is a promising reaction for obtaining valuable chemicals and the efficient long-term storage of solar radiation. In this work, we developed innovative TiO₂-based materials capable of base-free HMF photo-oxidation in water using simulated solar irradiation. The materials were prepared by combining microemulsion and spray-freeze drying (SFD), resulting in highly porous systems with a large surface area. The effect of titania/silica composition and the presence of gold-copper alloy nanoparticles on the properties of materials as well as photocatalytic performance were evaluated. Among the lab-synthesized photocatalysts, Ti₁₅Si₈₅ SFD and Au₃Cu₁/Ti₁₅Si₈₅ SFD achieved the higher conversions, while the best selectivity was observed for Au₃Cu₁/Ti₁₅Si₈₅ SFD. The tests with radical scavengers for both TiO₂-m and Au₃Cu₁/Ti₁₅Si₈₅ SFD suggested that primary species responsible for the selective photo-oxidation of HMF are photo-generated electrons and/or superoxide radicals.     

Freeze–Thaw-Promoted Fabrication of Clean and Hierarchically Structured Noble-Metal Aerogels for Electrocatalysis and Photoelectrocatalysis

Noble-metal aerogels (NMAs) have drawn increasing attention because of their self-supported conductive networks, high surface areas, and numerous optically/catalytically active sites, enabling their impressive performance in diverse fields. However, the fabrication methods suffer from tedious procedures, long preparation times, unavoidable impurities, and uncontrolled multiscale structures, discouraging their developments. By utilizing the self-healing properties of noble-metal aggregates, the freezing-promoted salting-out behavior, and the ice-templating effect, a freeze–thaw method is crafted that is capable of preparing various hierarchically structured noble-metal gels within one day without extra additives. In light of their cleanliness, the multi-scale structures, and combined catalytic/optical properties, the electrocatalytic and photoelectrocatalytic performance of NMAs are demonstrated, which surpasses that of commercial noble-metal catalysts.     

Electron Configuration Modulation of Nickel Single Atoms for Elevated Photocatalytic Hydrogen Evolution

The emerging metal single‐atom catalyst has aroused extensive attention in multiple fields, such as clean energy, environmental protection, and biomedicine. Unfortunately, though it has been shown to be highly active, the origins of the activity of the single‐atom sites remain unrevealed to date owing to the lack of deep insight on electronic level. Now, partially oxidized Ni single‐atom sites were constructed in polymeric carbon nitride (CN), which elevates the photocatalytic performance by over 30‐fold. The 3d orbital of the partially oxidized Ni single‐atom sites is filled with unpaired d‐electrons, which are ready to be excited under irradiation. Such an electron configuration results in elevated light response, conductivity, charge separation, and mobility of the photocatalyst concurrently, thus largely augmenting the photocatalytic performance.     

Stable Ti3+ Defects in Oriented Mesoporous Titania Frameworks for Efficient Photocatalysis

By introducing a compatible reducing agent (2‐ethylimidazole) into a mono‐micelle assembly process, we present a type of ordered mesoporous TiO₂ microspheres that combines radially aligned mesostructure with Ti³⁺ defects in mesoporous frameworks. Such reductant acts as a building block of mesostructured frameworks and reduces Ti⁴⁺ in situ to generate defects during calcination, giving rise to the coexistence of bulk Ti³⁺ defects and an ordered mesostructure. The mesoporous TiO₂ has both excellent mesoporosity (a high surface area of 106 m² g^?1, a mean pore size of 18.4 nm) and stable defects with an extended photoresponse. Such integration of unique mesoscopic architecture and atomic vacancies provide both effective mass transportation and enhanced light utilization, leading to a remarkable increase in H₂ generation rate. A maximum H₂ evolution rate of 19.8 mmol g^?1 h^?1 can be achieved, along with outstanding stability under solar light.     

Photoinduced Specific Acylation of Phenolic Hydroxy Groups with Aldehydes

A convenient method is reported to specifically acylate phenolic hydroxyl groups through a radical pathway. When a mixture of an aldehyde and a phenol in ethyl acetate is irradiated with blue light in the presence of iridium and nickel bromide catalysts at ambient temperature, phenoxyl and acyl radicals are transiently generated in situ and cross‐couple to furnish an ester. Aliphatic hydroxy groups remain untouched under the reaction conditions.