Showing papers by "Qin Zhong published in 2021"

Carbon-Based Electrocatalysts for Efficient Hydrogen Peroxide Production

Abstract: Hydrogen peroxide (H2 O2 ) is an environment-friendly and efficient oxidant with a wide range of applications in different industries. Recently, the production of hydrogen peroxide through direct electrosynthesis has attracted widespread research attention, and has emerged as the most promising method to replace the traditional energy-intensive multi-step anthraquinone process. In ongoing efforts to achieve highly efficient large-scale electrosynthesis of H2 O2 , carbon-based materials have been developed as 2e- oxygen reduction reaction catalysts, with the benefits of low cost, abundant availability, and optimal performance. This review comprehensively introduces the strategies for optimizing carbon-based materials toward H2 O2 production, and the latest advances in carbon-based hybrid catalysts. The active sites of the carbon-based materials and the influence of coordination heteroatom doping on the selectivity of H2 O2 are extensively analyzed. In particular, the appropriate design of functional groups and understanding the effect of the electrolyte pH are expected to further improve the selective efficiency of producing H2 O2 via the oxygen reduction reaction. Methods for improving catalytic activity by interface engineering and reaction kinetics are summarized. Finally, the challenges carbon-based catalysts face before they can be employed for commercial-scale H2 O2 production are identified, and prospects for designing novel electrochemical reactors are proposed.

Recent Progress of CeO2−TiO2 Based Catalysts for Selective Catalytic Reduction of NOx by NH3

Abstract: Selective catalytic reduction of NOx with NH3 (NH3−SCR) is one of the widely used process to abate NOx emission from both stationary and mobile sources. Recently, CeO2−TiO2 based NH3−SCR catalysts due to their excellent medium and high temperature activities, high N2 selectivity and environmentally friendly, have attracted much attention as great candidate to replace the commercial VOx−TiO2 based NH3−SCR catalysts. During the past years, extensive works have been done to achieve the industrial commercialization of CeO2−TiO2 based NH3−SCR catalyst. In this review, we summarize the recent studies on the mechanism, deactivation, preparation and modification of CeO2−TiO2 catalyst. The focus of this review is the modification strategies on improving the catalytic performance of CeO2−TiO2 catalyst. By comparing the effect of different modification strategies on the catalytic performance of CeO2−TiO2 catalyst, the perspectives and challenges of CeO2−TiO2 based catalyst for NH3−SCR of NOx are discussed.

A Fe single atom on N,S-doped carbon catalyst for performing N-alkylation of aromatic amines under solvent-free conditions

Abstract: A green and gram-scale strategy has been developed for the synthesis of Fe single atom/N,S-doped carbon catalyst (Fe20-SA@NSC) via the pyrolysis of polyaniline (PAN)-modified Fe,S-doped ZIFs, in which the synthesis of ZIFs can be accomplished in water at room temperature. The as-prepared catalyst exhibits superior activity in the N-alkylation of amines with alcohols via a borrowing strategy under solvent-free conditions (TOF up to 13.9 h−1). Based on the HAADF-STEM and XAFS results, Fe in this material is dispersed as the single-atom Fe1–N4S1 site. According to the experimental and theoretical calculation results, the Fe1–N4S1 site displays a better borrowing hydrogen ability than other Fe sites owing to its higher electron density. In addition, this catalyst has excellent stability and recyclability, and no obvious loss in activity is observed after 7 runs.

Recent advances in bismuth-based multimetal oxide photocatalysts for hydrogen production from water splitting: Competitiveness, challenges, and future perspectives

Abstract: The efficient utilization of photocatalytic technology is essential for clean energy. Bismuth-based multimetal oxides (Bi2WO6, Bi2MoO6, BiVO4 and Bi4Ti3O12) have aroused widespread attention as a visible light responsive photocatalyst for hydrogen evolution due to their low cost, nontoxicity, modifiable morphology, and outstanding optical and chemical properties. Nevertheless, the photocatalytic activities of pure materials are unsatisfactory because of their relative small specific surface area, poor quantum yield, and the rapid recombination of photogenerated carriers. Therefore, some modification strategies, including morphological control, semiconductor combination, doping, and defect engineering, have been systematically studied to enhance photocatalytic H2 evolution activity in the past few years. Herein, we summarize the recent research progress on bismuth-based photocatalysts, pointing out the prospects, opportunities and challenges of bismuth-based photocatalysts. Eventually, we aims to put forward valuable suggestions for designing of bismuth-based photocatalysts applied in hydrogen production on the premise of consolidating the existing theoretical basis of photocatalysis.

A well-controlled three-dimensional tree-like core–shell structured electrode for flexible all-solid-state supercapacitors with favorable mechanical and electrochemical durability

Abstract: Although coupling highly pseudocapacitive species with flexible carbon substrates to fabricate hybrid electrodes holds promise for high-performance flexible supercapacitors, the structural collapse and performance degradation under repeated mechanical deformation remain a bottleneck to be tackled owing to the weak binding force between carbon and electroactive materials. Herein, well-controlled three-dimensional (3D) NS@NCCH tree-like core–shell microarrays grown on flexible and conductive Ni-plated carbon cloth (NPCC) are fabricated, with NiSe (NS) nanorods as the core and NiCo(CO3)(OH)2 (NCCH) nanosheets as the shell. The dense NS nanorod core in situ grown on NPCC, as a highly conductive and robust support, promotes electron transport as well as hindering the agglomeration of NCCH nanosheets. The NCCH nanosheet shell with a high specific surface area provides a bridge to combine the fast diffusion of electrolyte ions and ionic accessibility to the overall electrode surface. The synergistic contributions from the NPCC substrate and the core–shell NS@NCCH microarrays together with the natural gift of a 3D tree-like architecture enable the NS@NCCH/NPCC electrode to exhibit a high capacity of 6.89 F cm−2 (1642 F g−1, 228 mA h g−1) at 4 mA cm−2 and good rate performance. Furthermore, an assembled flexible all-solid-state asymmetric supercapacitor (FASSAS) based on the NS@NCCH/NPCC electrode retains an energy density of 53.8 W h kg−1 at a high power density of 15 kW kg−1 and exhibits excellent cycling stability with 91.5% capacitance retention after 5000 cycles. Especially, bending or twisting the FASSAS device to 180° causes negligible electrochemical property attenuation.

Flower-like 1T-MoS2/NiCo2S4 on a carbon cloth substrate as an efficient electrocatalyst for the hydrogen evolution reaction.

Abstract: The 1T-MoS2/NiCo2S4 composite in situ grown on carbon cloth (CC) was successfully prepared by a two-step hydrothermal method as an efficient electrode for the hydrogen evolution reaction. The morphology and composition characterization show that the composite has a flower-like structure with a large number of edges and surfaces exposed, and the content of the 1T phase in MoS2 is 63%. 1T-MoS2/NiCo2S4/CC exhibits an overpotential of 107 mV at 10 mA cm−2, and a Tafel slope of 66.4 mV dec−1 in an alkaline electrolyte. After continuous electrolysis for 24 h at an overpotential of 170 mV, 86% of the original current density was retained in an chronoamperometry measurement. The outstanding catalytic performance of the composite is ascribed to its unique structure, high 1T-MoS2 content and the synergistic catalysis between 1T-MoS2 and NiCo2S4. This work provides a facile and effective strategy for fabricating the 1T-MoS2/NiCo2S4/CC composite and demonstrates that the composite is expected to be a competitive non-noble HER catalyst.

Competition of propylene hydrogenation and epoxidation over Au-Pd/TS-1 bimetallic catalysts for gas-phase epoxidation of propylene with O2 and H2

Abstract: Au and Pd play a collaborative effect in the formation of H2O2 from H2 and O2, which is beneficial for the gas-phase epoxidation of propylene over Au-Pd/TS-1 (i.e., Au-Pd bimetallic nanoparticles supported on titanium silicalite-1). However, the introduction of Pd into Au/TS-1 makes this reaction more complicated. In this work, GC–MS results demonstrated the presence of propylene hydrogenation. A small amount of O2 was found to significantly promote the propylene hydrogenation over Au-Pd/TS-1, while O2 concentration had less effect. Four catalysts were designed to discuss the active sites on Au-Pd/TS-1. It was concluded that propylene hydrogenation preferentially occurred at Pd sites and propylene epoxidation occurred at Au-Ti sites. Based on the catalytic performance of Au-Pd/TS-1 at 100 °C, a four-stage model was proposed for the first time to reveal the competition between propylene hydrogenation and epoxidation. Moreover, the addition of CO could abate the propene hydrogenation over Au-Pd/TS-1.

Modification of Catalytic Properties of Hollandite Manganese Oxide by Ag Intercalation for Oxidative Acetalization of Ethanol to Diethoxyethane

Abstract: The effect of addition of Ag to the catalytic properties of hollandite manganese oxide (HMO) was investigated for the oxidative acetalization of ethanol to diethoxyethane. Based on analysis with HR...