Electrochemical CO 2 reduction reaction (ECO 2 RR) with controlled product selectivity is realized on Ag−Cu bimetallic surface alloys, with high selectivity towards C2 hydrocarbons/alcohols (≈60 % faradaic efficiency...
详细信息
Electrochemical CO 2 reduction reaction (ECO 2 RR) with controlled product selectivity is realized on Ag−Cu bimetallic surface alloys, with high selectivity towards C2 hydrocarbons/alcohols (≈60 % faradaic efficiency, FE), C1 hydrocarbons/alcohols (≈41 % FE) and CO (≈74 % FE) achieved by tuning surface compositions and applied potentials. In situ spectral investigations and theoretical calculations reveal that surface-composition-dependent d-band center could tune *CO binding strengths, regulating the *CO subsequent reaction pathways and then the product selectivity. Further adjusting the applied potentials will alter the energy of participated electrons, which leads to controlled ECO 2 RR selectivity towards desired products. A predominant region map, with an indicator proposed to evaluate the thermodynamic predominance of the *CO subsequent reactions, is then provided as a reliable theoretical guidance for the controllable ECO 2 RR product selectivity over bimetallic alloys.
Achieving active and stable heterogeneous catalysts by encapsulating noble metal species within zeolites is highly promising for high utilization and cost efficiency in thermal and environmental catalytic reactions. R...
详细信息
Achieving active and stable heterogeneous catalysts by encapsulating noble metal species within zeolites is highly promising for high utilization and cost efficiency in thermal and environmental catalytic reactions. Ru, considered an economical noble metal alternative with comparable performance, faces great challenges within MFI-type microporous zeolites due to its high cohesive energy and mobility. Herein, an innovative strategy was explored that couples hydrothermal in situ ligand protection with stepwise calcination in a flowing atmosphere to embed ultrasmall Ru clusters anchored at K + -healed silanol sites (≡Si−Ru δ+ −O−K complexes) within 10-membered ring sinusoidal channels of MFI. Comprehensive experiments and theoretical calculations unveiled that the interplay between confined Ru clusters and MFI induces local strain in MFI, creating a unique catalytic microenvironment around the Ru clusters. This synergy interaction enhances alkane deep oxidation as the confined Ru clusters and the MFI microenvironment collectively pre-activate C 3 H 8 and O 2 , facilitate the cleavage of C−H and C−C bonds at low temperatures. Notably, the stable geometric and electronic properties of the confined Ru show exceptional thermal stability up to 1000 °C, rivaling fresh catalysts. These findings shed vital methodological and mechanistic insights for developing efficacious heterogeneous catalysts for thermal catalysis.
Nowadays, the use of biodiesel for diesel engines has been attracting researchers aiming to improve engine characteristics although the engine performance could be decreased while utilizing biodiesel. In this aspect, ...
Nowadays, the use of biodiesel for diesel engines has been attracting researchers aiming to improve engine characteristics although the engine performance could be decreased while utilizing biodiesel. In this aspect, optimizing the piston bowl geometry is one of the useful approaches to enhance the efficiency of the biodiesel-powered diesel engine. In this study, the standard piston of an existing diesel engine was modified into two different combustion bowls, namely Symmetrical Stepped Curved-V (SSCV) and Symmetrical Spline-V (SSV), to evaluate the CI engine performance powered with mixtures of sesame-originated biodiesel, diesel fuel, and tert -butyl hydroquinone (TBHQ) additive through two-stage experiment. In the first phase, experiments were carried out on two modified piston bowls powered by diesel and S20 (20% sesame biodiesel + 80% diesel fuel). Resultantly, SSV piston revealed superior engine characteristics to SSCV piston and standard piston due to enhanced air–fuel mixing and more complete combustion of SSV piston-based engine. Indeed, SSV piston operation exhibited an 8.68% of increased brake thermal efficiency (BTE), 6.54% of curtailed brake-specific fuel consumption (BSFC), 4.76% of lowered carbon monoxide (CO), 4.84% of decreased unburnt hydrocarbon (HC), and 2.22% of lowered smoke opacity but with increased nitrogen oxide (NOx) by 14.14% in comparison to diesel. In the 2nd phase, to control the NOx emission effectively, a TBHQ additive was added to the S20 sample at different proportions (500 mg and 1000 mg) to analyze the test engine behaviors with modified piston shapes. As a result, S20 + 500 mg TBHQ at 100% load improved BTE by 5.79% and reduced BSFC by 4.36% in the case of SSV piston. Moreover, it curtailed emissions of CO, HC, NOx, and smoke opacity by 13.33%, 15.49%, 12.09%, and 9.44%, respectively, when equated with diesel. Overall, S20 + 500 mg TBHQ could be thought of as a possible alternative fuel on SSV piston as it resulted in superior p
The development of highly active single-atom catalysts (SACs) and identifying their intrinsic active sites in oxidizing industrial hazardous hydrocarbons are challenging prospects. Tuning the electronic metal-support ...
详细信息
The development of highly active single-atom catalysts (SACs) and identifying their intrinsic active sites in oxidizing industrial hazardous hydrocarbons are challenging prospects. Tuning the electronic metal-support interactions (EMSIs) is valid for modulating the catalytic performance of SACs. We propose that the modulation of the EMSIs in a Pt 1 −CuO SAC significantly promotes the activity of the catalyst in acetone oxidation. The EMSIs promote charge redistribution through the unified Pt−O−Cu moieties, which modulates the d -band structure of atomic Pt sites, and strengthens the adsorption and activation of reactants. The positively charged Pt atoms are superior for activating acetone at low temperatures, and the stretched Cu−O bonds facilitate the activation of lattice oxygen atoms to participate in subsequent oxidation. We believe that this work will guide researchers to engineer efficient SACs for application in hydrocarbon oxidation reactions.
Red phosphorus is a promising photocatalyst with wide visible‐light absorption up to 700 nm, but the fast charge recombination limits its photocatalytic hydrogen evolution reaction (HER) activity. Now, [001]‐oriente...
详细信息
Red phosphorus is a promising photocatalyst with wide visible‐light absorption up to 700 nm, but the fast charge recombination limits its photocatalytic hydrogen evolution reaction (HER) activity. Now, [001]‐oriented Hittorf's phosphorus (HP) nanorods were successfully grown on polymeric carbon nitride (PCN) by a chemical vapor deposition strategy. Compared with the bare PCN and HP, the optimized PCN@HP hybrid exhibited a significantly enhanced photocatalytic activity, with HER rates reaching 33.2 and 17.5 μmol h −1 from pure water under simulated solar light and visible light irradiation, respectively. It was theoretically and experimentally indicated that the strong electronic coupling between PCN and [001]‐oriented HP nanorods gave rise to the enhanced visible light absorption and the greatly accelerated photoinduced electron–hole separation and transfer, which benefited the photocatalytic HER performance.
Cobalt ferrite (CoFe 2 O 4 ) spinel has been found to produce C 2 −C 4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO 2 with a rate of 1.1 mmol g −1 h −1 , selectivity of 29.8 % an...
详细信息
Cobalt ferrite (CoFe 2 O 4 ) spinel has been found to produce C 2 −C 4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO 2 with a rate of 1.1 mmol g −1 h −1 , selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe 2 O 4 reconstructs to a CoFe−CoFe 2 O 4 alloy-spinel nanocomposite which facilitates the light-assisted transformation of CO 2 to CO and hydrogenation of the CO to C 2 −C 4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery.
暂无评论