查看更多>>摘要：Crystal phase of semiconductor nanocatalysts has a great influence on their catalytic performance. Ag-based nanomaterials are fascinating electrocatalysts for CO2 reduction reaction (CO2RR) toward CO formation. However, the phase-dependent catalytic behavior of Ag-based electrocatalysts has not been studied so far. Herein, we report a crystal phase-dependent catalytic behavior of Ag2Se nanoparticles based on the successful synthesis of monoclinic (m-Ag2Se) and orthorhombic (o-Ag2Se). Remarkably, m-Ag2Se nanoparticles deliver an enhanced CO Faradic efficiency up to 98.1 % at -0.90 V vs. RHE as well as the long-term stability under an extremely high current density, far exceeding that of o-Ag2Se. Theoretical simulations reveal that m-Ag2Se surface not only facilitates the adsorption and stabilization of ~*COOH species, but also tends to inhibit HER, thus accounting for the high activity and selectivity for CO formation during CO2RR. This work offers new insights into the facile design of electrocatalysts in catalysis via crystal phase structure regulation.
查看更多>>摘要：Palladium is unique in the electrocatalytic reduction of CO2 to formate because of its low or even near-equilibrium onset potential. However, the inevitably produced CO molecules poison and deactivate die catalyst surface, resulting in an insufficient operating lifetime (<30 min) for conventional and optimized Pd catalysts. Herein, we present a hydrogen-rich Palladium hydride catalyst (PdH_(0.5)/C) derived from a one-step solvothermal synthesis. This catalyst showed a 93.1 % faradaic efficiency towards formate at - 0.4 V (vs RHE). The working lifetime reached a record of 4 h, which was ～15 times longer than a commercial Pd catalyst and outperformed all previous Pd-based electrocatalysts for CO2-HCOO~- conversion. The high CO tolerance was attributed to the selectivity improvement induced by lattice hydrogen and die weak CO adsorption strength on diverse active sites (i.e. kink, step, and terrace). Isotopic analysis revealed a direct participation of the lattice hydrogen in the protonation of CO2 molecules in formate formation.
查看更多>>摘要：In this work, we first report synthesizing a series of single-atom metals (covering main-group, transition, precious, and rare earth metals) photocatalysts M_(SA)/TiO2 using a simple, efficient, and high-yield mechanochemistry (high-energy ball milling) and evaluate their efficiency towards CO2 photoreduction. In the synthesized single-atom catalyst (SAC), the CH4 yield from CO2 photoreduction using Pd_(SA)/TiO2 reaches as high as 271.6 μmol·g~(-1)·h~(-1) with the selectivity of ～98.0%, far surpassing those of conventional Pd clusters and nano-particles. The experimental results and density functional theory (DFT) calculations reveal that the strong adsorption at single-atom catalytic sites (Pd) leads to significant bending of O=C=O bond angle from 180.0 to 151.0 ° and length from 1.16 to 1.20 A. The induced deformation greatly 'energizes' the CO2, thus reducing the kinetic energy barrier significantly and offering high catalytic activity. Meanwhile, combined with in-situ Fourier-transform infrared (FT-IR), a rational reaction pathway of CO2 photoreduction over efficient SACs is proposed.
查看更多>>摘要：Much attention has been drawn to develop efficient poly(ethylene terephthalate) (PET) recycling methods. Reported here is the solar-driven PET recycling coupled with H2 production with carbonized polymer dots-graphitic carbon nitride (CPDs-CN) as catalyst. PET plastic is a 'greener' alternative feedstock where its hydrolytic monomer ethylene glycol is converted into high added-value chemicals, mainly including glycolic acid, glycolaldehyde and ethanol; meanwhile, H2 is produced from water splitting. The monomer terephthalic acid yield reaches 304.7 ± 17.2 μmol, exceeding the value of the catalyst-free group nearly twofold. Increased H2 production rate upon hybridization with CPDs is achieved (1034 ± 134 vs. 291 ± 35 μmol g~(-1) h~(-1), respectively). The adopted strategy allows plastic waste to be used as a valuable feedstock for the sustainable production of value-added solar chemicals and solar fuels.
查看更多>>摘要：Design of highly efficient photocatalysts for CO2 reduction to renewable fuels has gained significant attention for energy sustainability and carbon neutralization. Here, we report the fabrication of hetero-metal oxide MCo2V2O8 hollow nanospheres through self-templating strategy and anion-exchange reaction. The as-prepared NiCo2V2O8 hollow nanospheres exhibit remarkable CO2 photoreduction, achieving a CO generation rate of 198.65 μmol g~(-1) h~(-1) (9.64 times higher than the undoped Co3V2O8) with 98.8% selectivity under visible light irradiation. Results of experiments and density functional theory (DFT) calculations show that addition of Ni in the hetero-metal oxide and their electronic interaction among d states decrease the bandgap to extend the light absorption, promote CO2 adsorption, and favor the separation of photogenerated charges with inhibited recombination. The in situ FT-IR and Raman spectral results identify the CO2 reduction pathway through COOH~* intermediate. This work sheds light on production of solar fuels via an efficient hetero-metal oxide strategy.
查看更多>>摘要：In this work, the centrosymmetry of Bi2S3 nanorods is broken due to the introduction of large quantities of S_i defects in the crystal lattice, which then endows the Bi2S3 nanorods with the ability to efficiently reduce Cr(VI) by piezocatalysis. Most importantly, the piezocatalytic reduction could be significantly boosted by applying an alternating magnetic field (AMF). The AMF coupled piezocatalysis is achieved by H2O2 and ·O_2~-. AMF is found to facilitate the separation of electrons and holes due to the magnetoresistance effect of Bi2S3 nanorods, thus remarkably enhancing the piezocatalysis by largely increasing the generation of H2O2. This work paves a new way for inducing the piezoelectricity of centrosymmetric materials by introducing defects and improving their catalytic activity through AMF, which has a great application potential in energy and environment fields.
查看更多>>摘要：Herein, an efficient domino synthesis for N-aryl pyrroles and tetrahydropyrroles from biomass-derived furan alcohols (i.e., 5-methyl furfuryl alcohol, and 2,5-bis(hydroxymethyl)furan) and nitrobenzenes was reported for the first time over metal phosphides. Dual active sites, including metal sites for nitro hydrogenation, acid sites for furan alcohol ring-opening determine the catalytic performance. Different from traditional tandem catalysts of Pd/C and HZSM-5 or Amberlyst-15 that suffer from binary competitive adsorption of furan and nitro groups on metal sites, as well as hydroxyl and hydrogenated amino groups on the acidic sites, metal phosphides show unexpected cooperative catalytic properties with the oriented synthesis of pyrroles over NiCoP and tetrahydropyrroles over Ni2P. Furthermore, the catalyst displays outstanding stability and recycling performance after 4 runs. This work demonstrates an effective strategy for governing reaction routes by selective activation and shows the powerful synergistic effect of hydrogenation and acid catalysis.
查看更多>>摘要：Herein, a rational design of 'cobalt/cobalt oxide/cobalt molybdate/nickel foam' multi-hierarchical tandem type electrocatalyst was achieved, where in situ reduced Co and CoO nanoparticles were dispersed uniformly and stabilized by CoMoO3 cuboids. This novel tandem type structure enables strong hydroxyl adsorption on CoO and moderated hydrogen adsorption on Co and therefore promotes the dissociation of water and the recombination of hydrogen intermediates into molecular hydrogen, respectively, and both act synergistically to catalyze the HER reaction. As a result, the current densities were up to 1.3 A cm~(-2) at only 173 mV overpotential in 1.0M KOH and 379 mV in 1.0 M PBS solution, respectively. The high rate H2 production of 4.35 ml min~(-1) at - 1.18 V (vs. SCE) and the outstanding performance of 10 A lasting for more than 800 h in a MEA eleetrolyzer both indicate the prospect for the usage in practical.
查看更多>>摘要：The integration of cathodic hydrogen evolution reaction (HER) with thermodynamically favorable anodic oxidation reactions offers a sustainable alternative for electrochemical valorization. Herein, the atomic Ni modified CoP electrocatalyst featuring an elaborate ordered macroporous superstructure with abundant built-in mesopores has been developed from the ordered macroporous ZIF-67 single crystals, of which the distinctive structural advantages lead to a high HER performance. When the catalyst further underwent an electrochemical reconstruction, an outstanding activity with high Faradaic efficiency up to 96% of formate for ethylene glycol oxidation reaction (EGOR) can be afforded in alkaline electrolyte, as well as in the complex electrolyte of polyethylene terephthalate (PET) plastic hydrolysate. Remarkably, an exotic energy-saving pair-electrolysis system coupling HER and EGOR was explored in the PET plastic hydrolysate by employing this bifunctional electrocatalyst for concurrent H2 and commodity chemical production. Our work may showcase the rational structural engineering of advanced electrocatalysts for multiple electrochemical applications.
查看更多>>摘要：Rhodium nanoparticles dispersed on a variety of composite supports, M_xO_y-Al2O3 (M: Ti, Y, Zr, La, Ce, Nd, Gd), were investigated for the propane steam reforming (PSR) reaction aiming to the efficient production of hydrogen. Addition of M_xO_y resulted in a significant promotion of intrinsic activity which varies depending on M_xO_y nature with the La2O3-containing sample exhibiting optimum performance. Selectivity toward methane side-product follows the same trend with that of PSR activity implying that methane is a key reaction intermediate. In situ DRIFTS experiments demonstrated that PSR reaction proceeds via intermediate formation of CHX species which are either hydrogenated toward CH4 or interacted with OH groups yielding formates that are further decomposed to H2 and CO_x. Rh/10%La2O3-Al2O3 and Rh/10%Gd2O3-Al2O3 catalysts were synthesized in the form of pellets and investigated using simulated liquefied petroleum gas (LPG) as feed, and proved to be promising candidates for the LPG steam reforming reaction.
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