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In-situ approach to fabricate BiOI photocathode with oxygen vacancies: Understanding the N2 reduced behavior in photoelectrochemical system
摘要： The adsorption and activation of N2 on the catalyst surface is a major problem in the process of photoelectrochemical (PEC) N2 reduction. Herein, we report a strategy to fabricate intrinsic BiOI (I-BiOI) photocathode with oxygen vacancies (OVs) (R-BiOI) by a facile in-situ method, and the R-BiOI was successfully selected as the model matrix for understanding the role of OVs in the PEC N2 reduction system for the first time. The correlation between carrier concentration/Lewis-base/active sites and OVs was in-depth demonstrated by Mott-Schottky plots and photoelectrochemical impedance spectroscopy (PEIS) results, meanwhile the Linear-sweep-voltammetry (LSV) data further confirmed the selectivity for active N2 over R-BiOI photocathode. The tandem built from BiVO4 photoanode and R-BiOI photocathode presented the desirable production rate of ammonia at about 1.4 mmol/m2/h, which is 1.3 and 2.9 times than that of I-BiOI (1.1 mmol/m2/h) and Pt (0.48 mmol/m2/h). Our findings have initially developed the proposed mechanism for the behavior of solar-electron-ammonia conversion and offered an alternative potential route for green N2 fixation.
关键词： Active sites,Lewis-base,Oxygen vacancies,BiOI,Photoelectrochemical (PEC) N2 fixation
更新于2025-09-23 15:23:52
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Unique 1D Cd <sub/>1?</sub><i> <sub/>x</sub></i> Zn <i> <sub/>x</sub></i> S@O-MoS <sub/>2</sub> /NiO <i> <sub/>x</sub></i> Nanohybrids: Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Evolution via Integrated Structural Regulation
摘要： Development of noble-metal-free photocatalysts for highly efficient sunlight-driven water splitting is of great interest. Nevertheless, for the photocatalytic H2 evolution reaction (HER), the integrated regulation study on morphology, electronic band structures, and surface active sites of catalyst is still minimal up to now. Herein, well-defined 1D Cd1?xZnxS@O-MoS2/NiOx hybrid nanostructures with enhanced activity and stability for photocatalytic HER are prepared. Interestingly, the band alignments, exposure of active sites, and interfacial charge separation of Cd1?xZnxS@O-MoS2/NiOx are optimized by tuning the Zn-doping content as well as the growth of defect-rich O-MoS2 layer and NiOx nanoparticles, which endow the hybrids with excellent HER performances. Specifically, the visible-light-driven (>420 nm) HER activity of Cd1?xZnxS@O-MoS2/NiOx with 15% Zn-doping and 0.2 wt% O-MoS2 (CZ0.15S-0.2M-NiOx) in lactic acid solution (66.08 mmol h?1 g?1) is about 25 times that of Pt loaded CZ0.15S, which is further increased to 223.17 mmol h?1 g?1 when using Na2S/Na2SO3 as the sacrificial agent. Meanwhile, in Na2S/Na2SO3 solution, the CZ0.15S-0.2M-NiOx sample demonstrates an apparent quantum yield of 64.1% at 420 nm and a good stability for HER under long-time illumination. The results presented in this work can be valuable inspirations for the exploitation of advanced materials for energy-related applications.
关键词： charge separation,1D hybrid nanostructures,photocatalytic hydrogen evolution,band alignments,active sites
更新于2025-09-23 15:22:29
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Highly efficient photocatalytic reduction of CO2 on surface-modified Ti-MCM-41 zeolite
摘要： Three dimensional microporous zeolites have attracted much attention in catalysis because of their large BET surface area and abundant pores. Herein, Ti-MCM-41 zeolites with different molar ratio of Si/Ti were synthesized, and the surface acidity and active sites were adjusted by the modification of basic-earth metal oxides, and noble metal nanoparticles. The photocatalytic activity and selectivity were evaluated by the reduction of CO2 to CH4 and CO. The results indicated that the efficiency and selectivity of CO2 photoreduction to CH4 of Ti-MCM-41 zeolites were 93 ppm·g-1·h-1 and 29% in the ratio Si/Ti=10 under keeping the zeolite structure, and which is much higher than that of P25 with the value of 24 ppm·g-1·h-1 and 23%. When the surface of Ti-MCM-41 zeolites was modified by different basic-earth metal oxides, the photo-reduction activity of CO2 to CH4 increased about 1.5 times with MgO modification, and the selectivity of CO2 to CH4 improved to 42%. Moreover, the photoactivity and selectivity enhanced to 8835 ppm·g-1·h-1 and 93% when the surface was further decorated by Pt nanoparticles, while the selectivity of CO2 to CO reached 94% when Pd was loaded. Our work reveal reasonably that adjusting the acidity and active site of the microporous zeolites is a highly efficient way to improve the photocatalytic efficiency of CO2 reduction.
关键词： Ti-MCM-41 zeolite,active sites,surface acidity,CO2 photoreduction
更新于2025-09-09 09:28:46
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Revealing molecular-level surface redox sites of controllably oxidized black phosphorus nanosheets
摘要： Bulk and two-dimensional black phosphorus are considered to be promising battery materials due to their high theoretical capacities of 2,600 mAh g?1. However, their rate and cycling capabilities are limited by the intrinsic (de-)alloying mechanism. Here, we demonstrate a unique surface redox molecular-level mechanism of P sites on oxidized black phosphorus nanosheets that are strongly coupled with graphene via strong interlayer bonding. These redox-active sites of the oxidized black phosphorus are confined at the amorphorized heterointerface, revealing truly reversible pseudocapacitance (99% of total stored charge at 2,000 mV s?1). Moreover, oxidized black-phosphorus-based electrodes exhibit a capacitance of 478 F g–1 (four times greater than black phosphorus) with a rate capability of ~72% (compared to 21.2% for black phosphorus) and retention of ~91% over 50,000 cycles. In situ spectroelectrochemical and theoretical analyses reveal a reversible change in the surface electronic structure and chemical environment of the surface-exposed P redox sites.
关键词： energy storage,pseudocapacitance,graphene,black phosphorus,redox-active sites
更新于2025-09-04 15:30:14
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Two Series of Microporous Lanthanide–Organic Frameworks with Different Secondary Building Units and Exposed Lewis Base Active Sites: Sensing, Dye Adsorption, and Magnetic Properties
摘要： Two series of new lanthanide complexes, {[Ln(L)1.5(H2O)]·DMA·4H2O}n (1-Ln, Ln = Tb, Gd, and Dy) and {[La2(L)3]·4H2O}n (2-La), were prepared successfully by Ln3+ ions and a N-heterocyclic dicarboxylic (2-pyrimidin-5-yl)terephthalic acid (H2L) ligand. The four complexes are three-dimensional (3D) microporous frameworks with different secondary building units (SBUs) and exposed Lewis base active sites. Topology analyses reveal that 1-Ln are the binodal (3,8)-connected tfz-d (43)2(46·618·84) nets and 2-La is a binodal (2,12)-connected (4)6(46·848·1212) net. The photoluminescence of 1-Tb, the dye adsorption of 1-Tb and 2-La, and the magnetism of 1-Dy have been well studied. The luminescent explorations indicate that 1-Tb is a highly efficient probe for sensing Fe3+ and Cr2O72?, respectively. Complexes 1-Tb and 2-La display the unique selective adsorption to Congo red (CR) dyes. Magnetic measurements further indicate that 1-Dy has a slow magnetic relaxation performance.
关键词： lanthanide complexes,dye adsorption,magnetism,photoluminescence,microporous frameworks,Lewis base active sites
更新于2025-09-04 15:30:14