查看更多>>摘要：In this study, phosphate FeCo(H3O)(PO4)(2) nanosheet arrays (NAs) were synthesized using an electrochemical strategy. FeCo(H3O)(PO4)(2) NAs as precatalyst could undergo significant self-reconstruction, including leaching of phosphate anions and electro-oxidation of Co2+ during anodizing at the potential range of oxygen evolution reaction (OER) in 1 M KOH solution, eventually resulting in the formation of Fe0.5Co0.5OOH NAs with low crystallinity. The high content of Fe in Fe0.5Co0.5OOH NAs promoted the formation of active Fe3+-O-Fe3+ motifs that increased OER occurrence. Additionally, Fe incorporation increased the ratio of the reaction rate constants of oxygen evolution to Co3+/Co4+ (k(OER)/k(M,ox)) and enhanced the reaction order on the hydroxyl ion. These factors significantly contributed to the outstanding OER catalytic performances of Fe0.5Co0.5OOH NAs.
查看更多>>摘要：Developing durable Si-based photoelectrochemical hydrogen evolution reaction in alkaline media is attracting attention in device-level water splitting, but still faces a trade-off between the alkalic corrosion resistance and light transmission for Si photocathodes. Herein, a synergetic strategy is proposed to employ an anti-reflective CoP film cocatalyst modulated via self-assembly of protective-layer WSx onto Si photocathode. The controllable WSx thin-film efficiently ensures the excellent anti-alkali corrosion of Si semiconductors, and serves as an appropriate nucleation base to modulate the structure of Co-P cocatalyst to possess anti-reflection. The optimal Co-P/WSx/Si photocathode exhibits an onset potential of + 0.47 V vs. reversible hydrogen electrode (V-RHE), a photocurrent density of -25.1 mA cm(-2) at 0 V-RHE, and superior durability of up to 300 h at 0 V-RHE in 1.0 M KOH electrolyte. These findings offer a facile and effective approach for the further development of durable Si-based photoelectrochemical devices.
查看更多>>摘要：BiVO4 is a promising and environmental-benign photoanode material. However, the photoelectrochemical properties of BiVO4 are confined to its low charge separation efficiency. Herein, we have developed a simple method to introduce stress into the BiVO4 photoanode via the change of the unit cell volume of VO2 near the phase transition temperature. In this way, the crystal structure of BiVO4 is caused to be distorted and thus improve the photoelectrochemical properties of the BiVO4 photoanode, making the surface photopotential of the BiVO4-V photoanode nearly double that of the bare BiVO4 photoanode. At room temperature, the photocurrent density of the BiVO4-V photoanode is 2.35 times that of the BiVO4 photoanode. Intriguingly, at 85 C, the photocurrent density of the BiVO4-V photoanode is as high as 6.8 times that of the BiVO4 photoanode. Moreover, the photocurrent density of the BiVO4-V photoanode could reach 80% of the theoretical photocurrent density of the BiVO4 photoanode at 85 C in the presence of the sacrificial agent Na2SO3. This work illustrates a new stress engineering strategy to improve the photoelectrochemical properties of BiVO4 photoanodes and is expected to be applicable to other semiconductor photoanodes.
查看更多>>摘要：Efficient oxygen evolution reaction (OER) electrocatalyst is essential for water electrolysis. Herein, high -performance NiFe-based layered double hydroxides (LDH), phosphide and sulfide OER pre-catalysts were fabricated and their distinct activity was unveiled. The as-prepared NixFe1-xS exhibits ultralow OER overpotential of 122 mV at 10 mA cm(-2) in 1 M KOH. The alkali-electrolyzer using NixFe1-xS electrodes achieve superior performance exhibiting a voltage of 1.46 V at 10 mA cm(-2). Experimental analysis reveals that, during OER, Fe dissolution into electrolyte occurs for NiFe LDH and NixFe1-xP, which were both converted into NiOOH, well explaining their similar activity. Interestingly, Fe dissolution is significantly mitigated in NixFe1-xS, forming partially oxidized Fe2O3/FeOOH species. Theoretical calculations confirmed that Fe2O3/FeOOH is responsible for the enhanced OER energetics of NixFe1-xS. These observations provide new insights on the distinct activity of NiFe-based electrocatalysts, guiding their rational design as well.
查看更多>>摘要：Heterojunction construction is a universal and effective approach to achieve high-efficiency photocatalysts. Towards these well-designed heterojunctions, modulation on steering dynamic charge transfer holds great promise in further performance stimulation. Herein, 2D/2D BiVO4/CsPbBr3 S-scheme heterojunctions, of which CsPbBr3 nanosheets (NSs) are in-situ face-to-face grown onto BiVO4 NSs, are designed as cornerstones for further carrier managements. Briefly, with controllable heterostructure regulation, an intimate heterointerface between BiVO4 and CsPbBr3 NSs with similar size can be obtained accompanied with a maximally intensified interfacial interaction, largely boosting charge transfer across the interfacial conjunction. Moreover, by further tailoring the intrinsic O vacancy (V-O(center dot center dot)) of BiVO4, the gradient Fermi level shift towards its valence band is finely tuned, yielding an enlarged Fermi level gap and an enhanced internal electric field (IEF) over BiVO4/CsPbBr3 hetero-junctions. Such an intensified IEF provides a powerful driving force for directional charge migration, resulting in high charge separation and utilization efficiency. Hence, the optimized BiVO4/CsPbBr3 S-scheme heterojunction features desirable accelerated dynamic carrier mobility, delivering comparably high CO2-to-CO conversion with a turnover number (TON) near 230 without any co-catalyst or sacrificial agent. The accelerated S-scheme charge transfer mechanism is revealed in detail by X-ray photoelectron spectroscopy (XPS), theoretical calculations, photo-irradiated Kelvin probe force microscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).
查看更多>>摘要：Pulse pyrolysis was carried out to realize real-time monitoring of CaO catalyst deactivation and regeneration in the catalytic pyrolysis of waste cooking oil (WCO) and free fatty acids (FFAs) based on the pyrolysis characteristics of feed stocks. The high unsaturation of the feedstock decreases the initial decomposition temperature and reduces the content of oxygen-containing compounds. CaO catalyst was completely deactivated after several times of pulse pyrolysis. During the pyrolysis of WCO, the catalytic activity of CaO did not recover after the pause of pulse pyrolysis. However, the catalytic activity all recovered during the pyrolysis of FFAs, but the rate of deactivation was accelerated. A large amount of Ca(OH)2 and CaCO3 were detected in the deactivated catalyst, and soluble coke was not detected. The research suggested that the change of crystal phases and agglomeration were the vital cause that impact the CaO catalyst stability.
查看更多>>摘要：The efficient mineralization of tetracycline (TC) and reaction mechanism were investigated by designing heterogeneous H2O2 center dot center dot center dot bridge linked with active sites in higher valency species. CuSi-BM60 was synthesized by anchoring Cu2+ on Si-O functional groups of MCM-48 by mechanochemical technology to assist electro-peroxone treatment (E-peroxone). Results suggested that catalysts as electron shuttle enhanced electron transfer and reactive oxygen species (ROSs) generation, showing a complete tetracycline (TC) degradation and excellent mineralization (73.2%, 60 min). Cu sites significantly raised the interaction with in-situ electro-generated H2O2, generating uneven electron cloud distribution by Si-O center dot center dot center dot Cu center dot center dot center dot HO-OH* bonding bridge, which enlarged H-O bonding length/angle near Cu and decreased orbital energy level gap. This work provided new insights into the complex of ball milling mediated Cu2+ with H2O2 accompanied by the cycle of H-O bonding cleavage and regeneration for efficient ROSs production during E-peroxone.
查看更多>>摘要：Although molybdenum selenide with controllable phase and morphology is pivotal for high-efficiency hydrogen evolution reaction (HER), at present, the MoSe2-based HER electrodes widely applied to all pH scale ranges and seawater are remaining tremendous challenge, due to the absence of active sites, poor conductivity of MoSe2 and the limitation of synthetic method. In this work, the large-scale Mo@(2H-1T)-MoSe2 monolithic electrode was successfully fabricated by etching Mo mesh in Na2SeO3 solution via a hydrothermal technique. Continuous phase and morphology modulation of MoSe(2 )on Mo mesh and the optimal synthetic condition are described to fabricate a state-of-the-art electrode Mo@(2H-1T)-MoSe2 with the piezo-flexoelectric coupling effect and heterostructure. The HER tests of Mo@(2H-1T)-MoSe2 in all pH ranges and seawater exhibit an enhanced HER activity, high stability and cycle durability, which benefit from the synergistic interaction of the piezo-flexoelectric coupling effect of hybrid 2H-1T phase of MoSe2 nanosheets and heterojunction. Operando EIS and theoretical calculations also revealed this viewpoint. This strategy can also be extended arbitrarily to the large-scale preparation of other heterostructured monolithic electrodes for high-efficiency HER, such as M@MSex (M = Ni, Cu, W, etc.). This study provides a simple, effective and low-cost approach to develop the state-of-the-art metal-based hetero-structured electrodes for other energy-related applications.
查看更多>>摘要：Recently, layered two-dimensional (2D) semiconductor materials composed of group 15 elements (pnictogens) are demonstrated as efficient photocatalysts in various applications. However, only little attention is given to the investigation of their catalytic properties, and even there is no example of the photocatalytic application of bismuthene so far. Here we report for the first time on the use of 2D bismuthene as a photocatalyst in a liquidphase organic transformation. 2D bismuthene is proven to be an efficient photocatalyst that can be operated under various reaction conditions including indoor light illumination, darkness, outdoors and low temperature for the photoredox C-H arylation of (hetero)arenes with high product yields. The presented bismuthene catalyzed photoredox C-H arylation protocol works efficiently on a broad substrate scope of (hetero)arenes with aryl diazonium salts bearing electron-withdrawing and electron-donating groups. Moreover, a density functional theory (DFT) study reveals mechanistic details that lie behind the catalytic activity of bismuthene.
查看更多>>摘要：Single atom catalysts (SACs) are emerging as efficient peroxide activators to eliminate water contaminants, yet the correlation between structure and catalytic activity remains elusive. Here we moderated the Fe sites on the carbon nitride and obtained a combination of single atoms and clusters sites on FeCN5 with the recorded methylene blue oxidation rate of 59.43 mg/L min(-1) via direct ultrafast H2O2 activation. The excellent performance was mainly ascribed to the high active sites exposure, self-creating acidic microenvironment, and assistance of leaching Fe. Nevertheless, excessive exposure of the catalyst at high pH may destroy the surface environment and inhibit H2O2 activation. To solve this issue, we developed a flow-through filter that reached nearly 100% pollutant degradation and H2O2 utilization and stability over 320 h when treating actual waste-water treatment. These findings provide profound insights into catalyst manipulation at atomic scales and the development of viable catalytic systems toward real-world application.
NSTL
Elsevier