The conventional process for producing ethanol through hydrogenation of diethyl oxalate (DEO) derived from coal-based synthesis gas requires operation under severe reaction conditions, including high temperatures, high pressures, and high H2/DEO ratios. This results in substantial energy consumption and necessitates the use of high-cost equipment, hindering the industrialization of this hydrogenation process. This study achieved dual electronic and structural regulation of copper-based catalysts through amine modification. This enhanced interactions between copper species and the functionalized support, strengthened metal-amine coordination, and significantly improved hydrogen adsorption. Consequently, the Cu sites became both conducive to H2 activation and resistant to deactivation, enabling highly efficient and stable hydrogenation reactions. Compared to other copper-ammonia catalysts, this catalyst achieves deep hydrogenation of DEO to ethanol under mild conditions (low temperature-the lowest reported-and low H2/DEO molar ratio), enabling near-complete conversion of DEO while maintaining high selectivity for ethanol, and shows no significant deactivation after 260 h of continuous reaction. Furthermore, the catalyst demonstrated exceptional performance in the hydrogenation of other substrates containing C-O bonds, providing a novel strategy for designing efficient catalysts for broad C-O bond hydrogenation processes.

Understanding the role of repulsive interactions between surface-trapped holes in photoelectrochemical (PEC) water oxidation reaction (WOR) kinetics is critical for advancing high-performance PEC systems. Using Au/ alpha-Fe2O3 photoanodes as a model, we elucidate how these interactions influence WOR kinetics. In situ transient absorption spectroscopy (TAS) measurements reveal that Au nanoparticles (NPs) significantly increase the surface density of FeIV=O species at Au/alpha-Fe2O3 interfaces, which act as key intermediates in WOR and directly enhance PEC performances. Quantitative surface interrogation scanning electrochemical microscopy (SI-SECM) tests demonstrate that the strengthened repulsive interactions between FeIV=O species on Au/alpha-Fe2O3 surfaces lower the activation energy for WOR, facilitating higher reactivity and enabling a faster third-order kinetic pathway of FeIV=O species during the O-O bond formation. Additionally, the highly accumulated FeIV=O species improve the oxidation capability of alpha-Fe2O3, which exhibit enhanced PEC performance in oxygen atom transfer (OAT) reactions and the degradation of antibiotic pollutants. These findings provide valuable insights into the role of repulsive interactions between surface-trapped holes in governing oxidation kinetics, highlighting their importance in promoting efficient charge carrier accumulation, utilization, and reactivity in PEC systems.

Styrene epoxidation is a crucial reaction in the chemical industry. However, low Faradaic efficiency (FE) and product selectivity severely limit the efficiency of (photo)electrocatalytic styrene epoxidation processes. This study designs an efficient photothermal catalytic system based on an Au/NiCo2O4 photoanode, which achieves the product selectivity of 98% and FE of 96% for bromide-mediated styrene epoxidation when the styrene conversion reaches 94%, surpassing most current reports on photoelectrocatalytic styrene epoxidation. A comprehensive mechanistic study reveals that the photothermal effect of the Au/NiCo2O4 photoanode enhances local temperature, which facilitates bromine species mass transfer, reduces reaction activation energy and accelerates the oxidation kinetics of Br-. This study elucidates the photothermal-driven reaction mechanism of styrene epoxidation, providing guidelines for designing efficient and stable photothermal catalytic technologies.

In this work, europium (III) complexes were synthesized by using different o-hydroxy-benzophenone ligands, namely 2-hydroxy-4-octyloxybenzophenone (HL1), 4-allyloxy-2-hydroxybenzophenone (HL2) and 2-hydroxy-4methoxybenzophenone (HL3). The structures and optical properties of the EuIII complexes E1, E2 and E3 were characterized by elemental analysis, infrared/fluorescence spectroscopy and mass spectrometry. The aggregation-induced emission properties from E1, E2 and E3 were systematically investigated in the acetone/ water binary mixtures. At the same time, the corresponding agglomeration behavior and self-assembly structures in the EuIII complex system was confirmed through scanning electron microscopy. Excellent luminescent performance was illustrated in sample of E1 (the luminescence quantum yield of 21.36 % in solid state) which should be attributed to the aggregation-induced emission from better self-assembly behavior with longer carbon chain in ligand. The results of ultraviolet aging resistance from E1 reveal that the self-assembly behavior could not only improve the aggregation-induced emission performance, but also enhance the photostability of EuIII complex compared with the traditional beta-diketone EuIII complex. This discovery may provide a facile strategy to design and prepare more promising rare earth complexes with good luminescence properties and strong photostability for application in solid state.

The anodic water oxidation reaction (WOR) is usually considered as the main hindrance due to its theoretically high redox potential and sluggish kinetics in an overall carbon dioxide reduction reaction (CO2RR) cell. However, the actual bias distribution between CO2RR and WOR half reactions in practice has not been systematically investigated. In this work, we find that in a photoelectrochemical (PEC) overall CO2RR cell with a hematite (alpha-Fe2O3) photoanode to catalyze WOR, although most of the applied bias is exerted on the Au cathode for satisfying the CO2RR thermodynamics, the cathode struggles to get sufficient voltage to drive CO production. Employing the value-added olefin epoxidation reaction to replace WOR and the introduction of Au plasmonic effect on the alpha-Fe2O3 photoanode allow for a controlled bias distribution between anode and cathode during the overall reaction process, enabling the cathode to reach the potential window for selective CO production under lower applied bias. Accordingly, the efficient oxygen atom utilization of CO2 is achieved and a model of oxygen atom transfer between the cathode and anode is proposed.

Developing an efficient and stable photocathode material for photoelectrochemical solar water splitting remains challenging. Herein, we demonstrate the potential of rutile TiO2 as a photocathode by Rh doping with visible light absorption up to 640 nm and an onset potential of 0.9 V versus the reversible hydrogen electrode. The dopant transforms the rutile host from an n-type semiconductor to a p-type one, as confirmed by the Mott-Schottky curve and kelvin probe force microscopy. Physical and photoelectrochemical analyses further suggest that the doping mechanism is dependent on concentration. Lower levels of dopants generate localized Rh3+, while higher levels favor Rh4+ that interacts more strongly with the O 2p orbitals. The latter is found not only to extend the visible light absorption range but also to facilitate charge transport. This work elucidates the role of the Rh dopant in adjusting the photoelectrochemical behavior of TiO2, and it provides a promising photocathode material for solar energy conversion.

Epoxides are one of the most important intermediates used in the production of valuable chemicals. Traditional preparation methods often rely on hazardous oxidants or extensive fossil fuel-powered thermal catalytic systems, resulting in significant waste production and CO2 emissions. Solar-driven photo(electro)chemistry is an emerging option for achieving the environmentally-friendly synthesis of epoxides. In this review, we firstly summarize the fundamental understanding of epoxidation reactions among various systems, including molecular catalysis, heterogeneous thermal catalysis and electrocatalysis. Then, we focus on the recent advances in the synthesis of epoxides achieved by photo(electro)chemical approaches. This review is concluded by the rational design of photoelectrochemical systems towards efficient epoxide synthesis.

Photo-electrochemical (PEC) and photocatalytic (PC) water splitting are promising solutions to achieve solar-powered hydrogen production. In the present work, to integrate the merits of PEC and PC techniques, a p-n conjugated two-electrode water-splitting system was miniaturized into one particle (denoted as electrode particle) for PC reactions. Specifically, a p-type Rh-doped strontium titanate (Rh:SrTiO3) photocathode material was selectively deposited on the electron-accumulated facet of a particulate n-type Mo-doped bismuth vanadate (Mo:BiVO4) photoanode with inserting a partly oxidized In@InOx interlayer as a grain binder and charge conductor. The photoexcited charge migration and accumulation were visualized through light-assisted Kelvin probe force microscopy. Benefited from efficient interfacial charge transfer and effective surface modification, visible light-driven PC overall water splitting into H-2 and O-2 was achieved over the prepared Mo:BiVO4/In@InOx/Rh:SrTiO3 electrode particle with an intense-light stability up to 40 h, an ambient pressure endurability from 5 to 95 kPa, and a solar-to-hydrogen energy conversion efficiency of 1.2 x 10(-2)%. This work develops a strategy of designing an efficient composite photocatalyst for PC overall water splitting and provides insights toward the enhancement of charge transfer efficiency across hetero-semiconductors.

The sluggish H2 O oxidation kinetics on photoanodes severely obstructs the overall solar-to-energy efficiency of photoelectrochemical (PEC) cells. Herein, we find a 10 to 55-fold increase of photocurrent by conducting ammonia oxidation reaction (AOR) on hematite (α-Fe2 O3 ) photoanodes under near-neutral pH (9-11) and moderate applied potentials (1.0-1.4 VRHE ) compared to H2 O oxidation. By rate law analysis and operando spectroscopic studies, we confirm the non-radical nucleophilic attack of NH3 molecules on high-valent surface Fe-O species (e.g., FeIV =O) and Fe-N species that produces NOx- and N2 , respectively, which overwhelms the nucleophilic attack of H2 O on surface FeIV =O and contributes to a high Faradaic efficiency of above 80 % for AOR. This work reveals a novel non-radical nucleophilic attack strategy, which is significantly different from the conventional indirect radical-mediated AOR mechanism, for the rational design of high-performance AOR photoelectrocatalysts.

Photoelectrochemical (PEC) performance of WO3 photoanodes for water splitting is heavily influenced by the orientation of crystal facets. In this work, mono-particle-layer electrodes, assembled by particulate WO3 square plates with highly uniform alignment along the (002) facet, improved PEC water oxidation kinetics and stability. Photo-deposition of Au along the cracks formed on the surface of the plates, which are the edges of {110} facets, was found to further enhance electron collection efficiency. Combination of these two strategies allowed the facet-engineered WO3 electrode to produce significantly higher efficiencies in charge separation and transfer than the electrode prepared without facet orientation. This work has provided a facile route for fabricating a structurally designed WO3 photoelectrode, which is also applicable to other regularly shaped semiconductor photocatalysts with anisotropic charge migration.

The solid solution of GaN and ZnO (GaN:ZnO) is a promising photocatalyst applicable to visible-light-driven overall water splitting. However, the band gap of active GaN:ZnO remains as large as ca. 2.7 eV because of the loss of ZnO during the widely applied NH3 nitridation process. Herein, particulate GaN:ZnO exhibiting a band gap of 2.3 eV was synthesized via calcination of a mixture of Ga2O3, Zn, and NH4Cl in a sealed evacuated tube. The synthesis method was also featured with a high nitrogen utilization rate of 87%. The prepared narrow-band-gap GaN:ZnO was active in the overall water-splitting reaction. In the presence of sacrificial reagents, the apparent quantum yields of GaN:ZnO at 420 nm for H2 and O2 generation were 5.1 and 14.3%, respectively. GaN:ZnO was applied as an oxygen evolution photocatalyst to construct a Z-scheme overall water-splitting system with SrTiO3:Rh as a hydrogen evolution photocatalyst, which achieved a solar-to-hydrogen energy conversion efficiency of 3.7 x 10-2% and a remarkable photochemical stability up to 100 h. This work provides an approach to the synthesis of narrow-band-gap GaN:ZnO solid solution and shows the potential of this material in H2 production from water under long-wavelength visible light.

The surface states of a semiconductor photocatalyst are essential for interfacial charge transfer in heterogeneous photocatalytic reactions. Here, we report that the light-driven hydrogen evolution reaction (HER) activity of 0.5 mol % Rh-doped rutile increases by more than 30 times compared with that of rutile when ascorbic acid is used as a sacrificial agent. Intensity-modulated photocurrent spectroscopy and surface photovoltage spectroscopy are employed to reveal the impact of surface states on the photo-oxidation reactions. It is found that the adsorption of ascorbic acid molecules dramatically reduces the activity of rutile due to coverage of the HER-active Ti sites. Nevertheless, for Rh-doped rutile, ascorbic acid neutralizes the Rh(IV) sites that would otherwise cause severe recombination of electron-hole pairs and resurrects its photocatalytic performance. This work demonstrates the key role of interfacial chemistry in photocatalytic reactions and provides a strategy for excavating the potential of various photocatalysts.

Facet regulation of the BiVO4 photoanode is an effective way to improve its charge separation efficiency. Herein, a BiVO4 photoanode structured by connecting a (040)-facet-oriented mono-grain layer to a conductive metal substrate was fabricated by particle engineering, namely a Langmuir-Blodgett assembly process followed by the particle transfer technique. The as-prepared electrode produced superior photocurrent and higher charge separation efficiency than that prepared by randomly accumulating the BiVO4 particles on a metal substrate. Impedance spectroscopy, time-resolved photoluminescence spectra, and theoretical analysis revealed that the (040)-facet-oriented photoelectrode had a relatively lower bulk charge transport resistance and higher electron-hole separation efficiency. Inserting Au nanoparticles into the BiVO4/substrate interlayer further enhanced its photo activity via accelerating electron transfer and preventing electron-hole recombination at the particle/substrate interface. A CoOx-loaded BiVO4/Au/Ti/Sn electrode fabricated by the particle engineering process evolved O-2 by water oxidation with a Faradaic efficiency of unity. This work provides a potential scalable strategy of enhancing photoelectrochemical activity by assembly of grain orientations, which is applicable to those semiconductor photocatalysts having face-selective anisotropic electron transfer property.

Incorporation of alien atoms into TiO2 is an effective means to extend its light absorption edge for utilizing solar energy sufficiently. Herein, taking rutile and anatase as precursors, respectively, Rh element was attempted to dope into TiO2 by an immersion-calcination process. The results showed that Rh species were readily immerged in the crystal structure of rutile at a temperature above 973 K, while they were constantly positioned on the surface of anatase in a separate form of Rh2O3 nanoparticle even at 1173 K. Density functional theory simulations revealed that the Rh-rutile sample owned a higher negative formation energy than Rh-anatase. Under visible light irradiation and in the presence of ascorbic acid as a sacrificial reagent, photocatalytic hydrogen evolution activity over Rh-doped rutile was about 50 times of that over Rh-doped anatase powders. The present work demonstrates the roles of the crystal phase in atom doping that eventually dominates photocatalytic activities.