查看更多>>摘要：It is highly desired to design high-performance bifunctional electrocatalysts for an efficient oxygen evolution reaction (OER) and urea oxidation reaction (UOR) as anode water electrolysis reactions, which can be used for hydrogen production by using urea-containing water. Herein, a novel electrocatalyst composed of amorphous Ni (OH)S nanosheets was prepared by hydrolysis of NiCl2(CH3CSNH2)4 at room temperature. From spectroscopic characterization and density functional theory (DFT) calculations, the Ni(OH)S catalyst contains a Ni3+-rich phase, which can significantly accelerate the reaction kinetics. The anode electrocatalyst shows excellent OER activity, generating 10 mA cm-2 with only 250 mV overpotentials. When employed as a UOR anode, it could reach 10 mA cm-2 at 1.34 V, 140 mV lower than OER. Notably, the Ni(OH)S/NF anode exhibits decent bifunctional UOR and OER activities and presents the lowest overpotentials compared to a NiFe-PBA/NF UOR catalyst and a typical RuO2/NF OER catalyst. This work provides a novel strategy for synthesizing amorphous Ni (III)-based sulfides nanosheets for bifunctional OER/UOR electrocatalysts, which is significant for efficient and stable hydrogen production by using urea-containing wastewater.
查看更多>>摘要：Selective hydrogenation of fatty acids is important for production of sustainable fuels and valuable chemicals as well as for the utilization of natural oils and fats. Generally, high reaction temperature (> 200 C) is required due to the weak polarizability and low reactivity of the carbonyl group of fatty acids. Here, we report an efficient catalytic system (Ni-Re/SBA-15 bimetallic catalyst) that realizes the low-temperature conversion of fatty acids to corresponding alcohols (reaction temperature: 150 C) and diesel-range alkanes (170 C) with high yields, surpassing the catalytic performance rendered by most of the catalytic systems reported so far. Detailed investigation into the nature of the catalyst showed that the superior activity originated from the formation of NiRe alloy, which improved the dispersion of metallic Ni, the H-2 activation ability and promoted the fatty acids/alcohols adsorption on the catalyst surface at low temperatures. More importantly, due to its strong electrophilicity, the fatty acids with highly electronegative carbonyl oxygen can be preferentially adsorbed on the catalyst surface than the fatty alcohols, which leads fatty acids to be converted preferentially. In this way, high catalytic efficiency and fatty alcohol selectivity can be obtained at a low temperature (150 C). Further increasing reaction temperature to 170 C, the reactant can be hydrodeoxygenated to form diesel-range alkanes. This developed NiRe/SBA-15 catalytic system highlights a great prospect for production of valuable fatty alcohols and alkanes from the conversion of bioderived fatty acids under mild conditions.
查看更多>>摘要：The nitrogen/oxygen self-doped porous biochar (NO/PBC) and NO/PBC supported CuFeO2 (CuFeO2-NO/PBC) were prepared and mixed as cathode catalysts for gas diffusion electrode (GDE) fabrication. The fabricated GDE could realize H2O2 electrogeneration and activate H2O2 to produce active radicals through NO/PBC and CuFeO2, respectively. The GDE with the NO/PBC to CuFeO2-NO/PBC ratio of 1:1 (CuFeO2-NO/PBC-GDE-1.0) possessed more superior catalytic performance for tetracycline degradation in heterogeneous photo-electro-Fenton (heteroPEF) system under visible light than other as-fabricated GDEs. The center dot & nbsp;OH was primary species, and center dot O-2(-) was auxiliary species for hetero-PEF degradation of tetracycline through CuFeO2-NO/PBC-GDE-1.0. The electron on the cathode surface and photoinduced electron could accelerate & nbsp; =Fe3+/=Fe2+ and =Cu2+/=Cu+ redox cycle, promoting center dot OH/center dot O-2(-)& nbsp;production and tetracycline degradation. The toxicity estimation of tetracycline and intermediates, TOC removal and Escherichia coli growth inhibition confirmed that the remission of overall toxicity, the inhibition of antibacterial property and the mineralization of tetracycline were achieved in hetero-PEF system.
查看更多>>摘要：Reduction pre-treatment at different temperatures were performed over Mo/HZSM-5 system before methane dehydroaromatiztion reaction. We have shown the crucial effect of reduction temperature on the final catalytic performance. Outstanding improvement in the aromatics conversion has been attained. Thus, H-2 formation form methane cracking reaction seems to be hindered for pre-treated catalysts. As a consequence, the deposition of coke in these samples appeared also notably suppressed. The optimum performance has been achieved for reduction pre-treatment at 550 degrees C. For this temperature, we have observed that the fraction of reduced Mo species is higher.
查看更多>>摘要：Constructing heterojunction nanocomposites with optimized active sites and interface electronic structures is promising for hydrogen evolution reaction (HER). Herein, we present an interface engineering strategy to fabricate two heterostructures, triphase MoSe2/NiSe-1 including 1T-MoSe2, 2H-MoSe2 and hexagonal phase NiSe (H-NiSe), and tetraphase MoSe2/NiSe-2 including 1T-MoSe2, 2H-MoSe2, H-NiSe and rhombohedral phase NiSe (R-NiSe). MoSe2/NiSe-1 exhibited remarkably enhanced HER activity with an overpotential of 30 mV at 10 mA cm(-2), and negligible voltage change even when operated for 40 h. The strong electronic synergistic interaction between the different interfaces of mixed MoSe2/NiSe greatly enhanced the HER performance. Density functional theory calculations helped rationalize why the combination of three phases is more active, by increasing the interface electron concentration, facilitating electron transfer and decreasing the free energy delta G(H2O) and delta G(H)*. This work provides a rational strategy to design and assemble stable and high-performance multiphasic heterojunctioned HER electrocatalysts.
查看更多>>摘要：Solar-driven photocatalytic production of hydrogen peroxide (H2O2) requires only sunlight, oxygen, and water, making it a green and sustainable alternative to conventional H2O2 production processes. We present photo-catalytic carbon dots (CDs) as a new candidate for high-performance H2O2 production. Owing to the generation of an excellent charge carrier and the presence of various oxygen-containing functional groups, CDs showed an outstanding H2O2 production capability of 609.4 mu mol g(-1) h(-1) even in the absence of an electron donor, demonstrating promising self-electron-donating capabilities. Hydroxyl groups on their surface, in particular, serve a dual role as photocatalytic active sites and as electron and proton donors toward the oxygen reduction reaction (ORR). The photocatalytic activity of CDs was significantly improved to 1187.8 mu mol g(-1) by functionalizing their surfaces with anthraquinone (AQ) as a co-catalyst; it promoted the charge carrier separation and electrochemically favored the two-electron pathway of ORR. These carbon-based metal-free nanohybrids that are a unique combination of CDs and AQ could offer insights into designing efficient photocatalysts for future solar-to-H2O2 conversion systems.
查看更多>>摘要：This work reports a strategy to promote the low-temperature CO2 methanation on the Ni-based catalyst by tuning the surface oxygen vacancy and medium-strength basic sites of the CeO2 support and thus changing the reaction pathway. La species was introduced into CeO2 support and calcined at 600 degrees C (CeO2-La-600) to form a La-Ce-O solid solution with a thin La2O2CO3 layer on the surface, generating more basic sites and oxygen vacancies. This unique structure facilitated the adsorption and direct dissociation of CO2. Over Ni/CeO2-La-600, the reaction follows the HCOO* and *CO pathways, while over Ni/CeO2-600, the reaction occurs via the HCOO* pathway only. The decomposition of CO2 * to *CO is energetically more favorable than hydrogenation to HCOO* on Ni/CeO2-La-600, resulting in its higher catalytic performance at low temperatures. This work unravels the complex interplay among oxygen vacancy, basic site, and reaction pathway in CO2 methanation over the Ni-based catalysts.
查看更多>>摘要：With exciting functionality, topological defects in ferroic system have attracted significant attention. Under proper design, the emergence of polar domain walls in non-polar ferroelastics enables a flexo-phototronic effect. In this study, we revealed ferroelastic twin texture with localized flexoelectric effect in centrosymmetric epitaxial BiVO4 film. Supported by photodeposition and localized photocurrent analysis, we found the flexoelectric effect confined at domain wall area facilitates the photocarrier transport and the flexo-phototronic mechanism was further supported by dye-degradation and generation of reactive radicals. This work not only provides new insights into the introduction of flexo-phototronic effects in non-polar materials, but also sheds light on the use of material inhomogeneity for acquiring multifunctionality.
查看更多>>摘要：The donor-acceptor (D-A) interactions between the triazine ring unit and adjacent substituents is one of the decisive factors that affect the performance of triazine-based conjugated polymer photocatalysts. Herein, we design and synthesize novel conjugated polymers by introducing electron-drawing 1,3,4-oxadiazole units into 1,3,5-triazine-based pi-conjugated skeletons for photocatalytic hydrogen production. Compared with the bulk polymer, the modified photocatalysts show extended visible light harvesting and boosted charge separation. Notably, under the irradiation of full-spectrum solar light, as-synthesized polymer with bi-1,3,4-oxadiazole linkage (denoted as TCP-BOXD) shows a highly improved hydrogen-evolving rate up to 3000 mu mol g(-1) h(-1). Furthermore, DFT calculation reveals that N atoms in the introduced 1,3,4-oxadiazole unit, coupled with those in the triazine ring, act as synergistic bi-active sites for superior photocatalytic hydrogen production. Our findings may help the rational design and controllable synthesis of novel triazine-based conjugated polymers for photocatalysis.
Gong, Zi-JieNarayana, Yemineni S. L., VLin, Yen-ChunHuang, Wei-Hsiang...
12页
查看更多>>摘要：Ruthenium-based metallo-supramolecular polymers (Ru-MSPs) were synthesized by complexing Ru ions with 1,4-bis(1,10-phenanthrolin-5-yl)benzene ligands for heterogeneously catalytic transfer hydrogenation of carbonyl compounds with formate. The degree of polymerization and the local environment of Ru atoms in RuMSP were tailored by tuning the ligand/metal ratio and the synthesis temperature/period. The coordinativelyunsaturated Ru atoms are identified as the active centers in Ru-MSP for carbonyl reduction. Ru-MSP is much more active than Ru-based counterparts including its monomeric analogue, which is attributed to (1) the higher electron density in Ru atoms that facilitates the selective dehydrogenation of formate via C-H dissociation, and (2) the lower LUMO of ligand moieties that activates the carbonyl oxygen via Lewis acid-base interactions. Furthermore, Ru-MSP displays high reusability and capability of catalyzing a wide scope of carbonyl compounds. These findings demonstrate that the rationally-designed polymerization is a promising approach to heterogenize the catalytically active metal complexes with enhanced performance.
NSTL
Elsevier