查看更多>>摘要：Herein, we report an oxygen vacancy (OVs)-rich Nb2O5 semiconductor (OVs-N-Nb2O5) as a bifunctional heterogeneous photocatalyst for unprecedent synthesis of a-sulfonyloxy ketones via oxidative alkene difunctionalization with sodium sulfinate under visible light irradiation and ambient conditions. A broad set of aromatic and aliphatic alkenes was efficiently difunctionalized into diverse a-sulfonyloxy ketones in high yields with a good functional group tolerance. The catalyst OVs-N-Nb2O5 is highly stable and could be easily recovered for at least 6 successive recycles with maintaining photoactivity and selectivity. Experimental and theoretical investigations reveal that the presence of OVs not only accelerates the separation and transfer of photogenerated electron-hole pairs, but also promotes O-2 adsorption and activation to form long-lived superoxide anion radical (O-2 center dot), which greatly boosts the reaction and modulates the reaction pathways together with the intrinsic Lewis acid sites, thereby resulting in an improved reaction activity and excellent selectivity to the desired product.
查看更多>>摘要：The simultaneous integration of electronic regulation and architectural engineering in one electrocatalyst represents a powerful leverage to concurrently boost the electrocatalytic performance towards overall water splitting. We herein rationally fabricate Sn4P(3)/Co2P "stalk "- "cap "-typed nanoarrays (Sn4P(3)/Co2P SCNAs) with abundant heterointerfaces and elaborately implanted "caps ". The nanoarrayed structure can substantially enlarge the exposure of active sites and promote the mass/electron transport, thus accelerating the reaction kinetics. Moreover, the purposely grafted "caps " are beneficial to increase the hydrophilicity/aerophobicity, which facilitate the water affinity and release of generated gas bubbles. Accordingly, the obtained Sn4P3/Co2P SCNAs deliver exceptional electrocatalytic performances towards the HER and OER, as reflected by the over potentials of 45.4 and 280.4 mV at 10 mA cm(-2), respectively. More impressively, the two-electrode electrolyzer assembled by freestanding Sn4P(3)/Co2P SCNAs requires a cell voltage of 1.56 V at 10 mA cm(-2) and exhibits superior stability and full reversibility, holding great potential in practical water electrolysis.
Kierzkowska-Pawlak, HannaKruszczak, EwelinaTyczkowski, Jacek
12页
查看更多>>摘要：Addressing the challenge of increasing the rate of CO2 capture by accelerating the hydration process, we proposed the use of a new class of heterogeneous inorganic catalysts for this purpose. The presented research focused on Co3O4-based nanocatalysts produced by low-pressure plasma deposition (PECVD) in the form of thin films that can be deposited on any structured packing. The kinetic studies of this process were performed by bubbling CO2 through pure water with catalytic or inert packing, measuring changes in pH value over time. The developed kinetic model described the experimental data very well and showed that the reaction at the interface between the CO2 bubble and the catalyst surface is responsible for the catalytic effect. Studies of the molecular structure of the catalyst surface, carried out by the XPS technique, showed that the chemisorbed H2O clusters on this surface are the active centers for the interaction with gaseous CO2.
查看更多>>摘要：The low defect content and poor oxygen mobility of perovskite catalysts limit its application in VOC elimination. Herein, we report a strategy involving defect engineering route following an easy urea treatment method to enhance the propane oxidation performance of perovskite catalysts. The constructed LaCoO3-D43 exhibits superior catalytic activity (T-90 = 309.3 degrees C), the T-90 value is 150 degrees C lower than that of LaCoO3, and excellent thermal stability against CO2 and H2O. Experimental results revealed that the urea pyrolysis resulted in the generation of La and O defects and rich surface-active Co species in high-valence states, increasing the utilization of Co active sites. DFT calculations show that the exposed Co surface is conducive to the adsorption and dissociation of oxygen and propane. This work provides a defect engineering strategy to effectively activate perovskite catalysts performance, and can be generalized for the fabrication of other types of perovskite catalysts.
查看更多>>摘要：It is an ideal route to generate hydrogen peroxide (H2O2) via selective 2e(-) ORR powered directly by sunlight. In this work, we synthesized a metal-free N-doped gamma-graphyne catalyst and wired it with n-type semiconductor photoanodes. The introduction of sunlight could lower the onset bias of oxygen reduction reaction (ORR) up to 0.32 V and H2O2 was steadily produced without any sacrificial agents and bias. The 2e(-) ORR selectivity of N-doped gamma-graphyne catalyst was bias dependent, and it reached about 74% at 0 bias in 0.1 mol.L-1 KOH. Theoretical calculations showed that in-situ pyridinic-N in N-doped gamma-graphyne acted as the active site for ORR, accelerating the rate-determining step of proton abstraction. The H2O2 yield reached as high as 7.47 mmol.h(-1) g(-1), outperformed the reported traditional photocatalytic syntheses of H2O2.
Fierro-Gonzalez, Juan C.Solis-Garcia, AlfredoZepeda, Trino A.
10页
查看更多>>摘要：ZrO2-supported rhodium nanoparticles prepared by impregnation of RhCl3 are active for CO2 methanation at temperatures above 180 degrees C. Infrared (IR) spectra recorded during catalysis allowed identification of Rh carbonyls and formate species bonded to the support. To verify their individual involvement in the catalysis, their transformations were investigated by IR spectra measured as a sample of ZrO2-supported Rh was treated with CO and isotopically labelled formic acid. The data indicate two coexisting reaction routes: a dissociative route in which CO2 reacts on the Rh sample to give Rh carbonyls, and an associative route in which the CO2 molecule is activated on the support, in the form of bicarbonate species that are hydrogenated to give formate species prior to methane formation. Our data show that labelled formates are transformed into Rh-13CO, thus connecting the dissociative and associative catalytic routes. The results indicate the existence of a dual mechanism for CO2 methanation.
Chun, HojeHan, ByungchanShanmugam, SangarajuYesudoss, David Kumar...
10页
查看更多>>摘要：Electrochemical ammonia synthesis through the atmospheric nitrogen reduction reaction (NRR) is a promising method for sustainable fertilizer and carbon-free hydrogen energy carriers. The inevitable selectivity gap against hydrogen evolution reaction and inert nitrogen (N-2) hinders the device-level usage of nitrogen cathodes. In this work, we report engineered electrocatalyst/support interface of NbTiO4 nanoparticles supported on nitrogen doped carbon nanorods (NbTiO4@NCNR) to catalyze NRR. Insisted by the pitfalls to rationally design N-2 reduction catalysts, the strong catalyst-support interaction strategy is adapted to tune the selectivity towards NRR. Electrochemical tests reveal that NbTiO4@NCNR hybrid accelerates a 10-fold increase in N-2 selectivity compared to pure metal oxide. Using first-principles calculations, we identify the underlying mechanism of enhanced performance: bridging bonds in the interface as electron transport channels to promote the N-2 reduction kinetics. Essentially, this study provides an insight into how to overcome the immense kinetic barrier of NRR using smartly engineered interfaces of hybrid materials.
查看更多>>摘要：Ammonia is an indispensable chemical to the ecosystem and human beings. Storing solar energy in N-H bonds in NH3 is a promising sustainable alternative to the energy-consuming Haber Bosch process. However, nitrogen photofixation with this strategy still suffers from several unsolved issues, such as high-energy consumption with carbon footprint, short lifetime of photocatalysts, and nitrogen contamination in redox reactions. In this study, a room-temperature strategy is developed to two-dimensionally assemble the diminutive CoO-Co3O4 mixed-oxide composites on reduced graphene oxide. They proffer great surface area and deep-red-light absorbing defect states, which enable them to exhibit over 14 times higher photoactivity than template-free single components. The unveiled photoreaction-induced cation oxidation is reversely triggerable by photo-reactivating Co3O4 back to active CoO, with well-maintained photoactivity after six-cycles. All these room-temperature processes, from catalyst synthesis, nitrogen photofixation, to catalyst reactivation, offer facile way towards upscaling and hold great promise for practical zero-emission N-2 photofixation.
查看更多>>摘要：Reductive catalytic conversion of DDT (p,p'-dichlorodiphenyltrichloroethane) was studied under ambient conditions in a hydrogen atmosphere using platinum and palladium deposited on several supports, in particular on porous alumina and silica. Almost complete hydrodechlorination and hydrogenation of DDT and its dehydrochlorination byproduct DDE (p,p' -dichlorodiphenyldichloroethene), leading to the formation of diphenylethane (with Pd) and dicyclohexylethane (with Pt), were observed at ambient temperature within minutes or hours. Rapid hydrodechlorination also takes place after depositing DDT and the metal component on separate particles and mixing them mechanically. This long-range reactivity can be explained either by a fast surface diffusion of DDT or DDE, or by hydrogen spillover. Irrespective of the mechanism, the reactivity thus bridges the barrier across solid particle interfaces. Most findings indicate the fast diffusion of target compounds as dominant mechanism for the observed long-range reactivity.
查看更多>>摘要：In this study, the catalytic performance of helical-form carbon fiber cloth anode loaded with atomic Fe@MoS2 (Fe@MoS2/CFC (h)) in piezocatalytic fuel cell (Pz-FC), improved 1.27 times with aeration as the piezo-driving force. The above Pz-FC with 0.5 mM peroxymonosulfate (PMS) and Xe-lamp irradiation forming a PMS-piezophotocatalytic fuel cell (PMS-Pz-PFC) system, removed 92.8% berberine in 60 min and generated power density that were respectively 2.04-fold and 8-fold higher than the PMS-Pz-PFC using MoS2/CFC (h) as the anode. Experiments showed that atomic Fe promoted piezo-photocatalysis of the helical-design anode significantly to accelerate the activation of PMS. Moreover, with 0.5 mM PMS, remarkable enhancement of electricity generation (more than 500 times difference) and pollutant degradation (by 40-50%) were achieved. The drastic synergy of piezoelectric catalysis in enhanced advanced oxidation has great practical application potential.
NSTL
Elsevier