Balu, SridharanChen, Yi-LunChen, Shih-WenYang, Thomas C. -K....
15页
查看更多>>摘要：Metal vanadate (MVO4) and graphitic carbon nitride (g-C3N4) semiconductor materials have attracted much interest due to their tremendous physicochemical and photocatalytic performances. In this prospect, BixFe(1_ x)VO(4) were prepared by mixing cation precursors (Bi and Fe) in different proportions (x = 0.7; 0.5; 0.3) via a simple one-pot hydrothermal route and impregnated on the surface of sulfur-doped g-C3N4(SCN) to attain a wide range of solar absorption and effective charge separation. Several spectroscopic techniques were used to analyze the physicochemical and optoelectronic properties of as-synthesized photocatalysts. The photocatalytic activities of as-synthesized photocatalysts were evaluated by photoelectrochemical oxygen evolution reactions (OER) and photodegradation of roxarsone (ROX). This work aims to investigate the formation, photocatalytic performance, and rational mechanism of BixFe1-xVO4/SCN photocatalytic nanocomposites. Among different BixFe(1_ x)VO(4) (x = 0.7; 0.5; 0.3), the BixFe(1_ x)VO(4)/SCN (Bi/Fe = 0.5) nanocomposite results in 85.66% of ROX photodegradation within 90 mins under visible-light irradiation. The photocatalytic performance of the nanocomposite is about 2.49, 2.87, 3.48 folds higher than that of pristine g-C3N4, BiVO4, and FeVO4 samples, respectively. The photo electrochemical OER results suggest the higher photocurrent density at 1.23 V (vs NHE) was achieved by BixFe(1_ x)VO(4)/SCN (0.987 mA cm(-2)) nanocomposite, and which is 16.73, 5.11, and 6.16 times higher than that of CN (0.059 mA cm(-2)), BiVO4 (0.193 mA cm(-2)), and FeVO4 (0.160 mA cm(-2)), respectively. The XPS and photo electrochemical (PEC) analysis depict the higher donor densities (ND) and excellent charge separations through type-II heterojunction of the BixFe(1_ x)VO(4) nanocomposite.
查看更多>>摘要：A gas-solid and postsynthetic modification was proposed to enrich surface bridging hydroxyls (OHB) on TiO2 using ozone. It was found that the adsorbed ozone and its decomposition into oxygen atoms on oxygen vacancies would induce water dissociation and form OHB, narrowing the bandgap and enhancing the photoresponse. The increased OHB significantly doubled the efficiency of photogenerated charge carriers transfer, thus generating more reactive oxygen species. Additionally, OHB provided more adsorption sites for toluene, contributing to the excellent activity and stability. The degradation pathways of toluene containing OH addition and hydrogen abstraction were proposed based on in situ DRIFTS results. Ozone treatment was more effective than other reported surface treatments, and presented a universal improvement on both gas-solid and liquid-solid photodegradation. This work provides a facile, effective, and alternative strategy for the targeted regulation of OHB on TiO2 under mild conditions and insight into the mechanism underlying the process.
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：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：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：Rationally design and exploration of bifunctional electrocatalysts with excellent performance towards water splitting is significant for hydrogen energy economy. Herein, a novel Au/Ni3S2 heterostructure catalyst that was composed of self-supported Ni3S2 nanosheets decorated with Au nanoparticles on Ni foam was fabricated. The bifunctional catalyst exhibited excellent catalytic activities towards oxygen evolution reaction (230 mV @ 10 mA cm(-2)) and hydrogen evolution reaction (97 mV @ 10 mA cm(-2)) in 1 M KOH. The electrolytic tank using the bifunctional catalyst only required 1.52 V to deliver 10 mA cm(-2) and sustained for 60 h, outperforming most of advanced bifunctional catalysts. The X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations validated that the strong electronic coupling at the interface could modulate the electronic structure of Ni3S2, thereby optimizing the free energies of the adsorbed intermediates. This work provides an atomic-scale insight into the structure-properties relation of a promising heterostructure catalyst for water splitting.
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