查看更多>>摘要：Heterostructure materials are increasingly utilized in solar energy conversion to pursue high efficiency and longterm stability. The charge transfer across interfaces gives rise to major energy loss arising from non-ideal interfacial effects, i.e., high interfacial energy barrier and low interfacial contacting area. Herein, we demonstrate a facile interface engineering strategy to eliminate non-ideal interfacial effects. A heterojunction of CN@CP25 is constructed via polyphenol-assisted assembly of titania (P25) and carbon nitride (CN). The uniform dispersion of P25 on CN enlarges the interfacial contacting area of 3.2-fold compared with random dispersion, while the transformation of polyphenols into conjugated carbon facilitates the interfacial charge transfer by switching a 0.4 eV Schottky contact to a 0.1 eV Ohmic contact between CN and P25. A 2.5-fold enhancement of charge transfer flux is obtained with an initial reaction rate of 5185 mu mol h-1 g-1 for photocatalytic nicotinamide regeneration.
查看更多>>摘要：This study investigates the electrochemical dechlorination of trichloroethylene (TCE) to non-toxic and valueadded ethane by self-activated Ni(OH)(2) cathode. The Ni(OH)2 cathode was fabricated by drop-casting the as synthesized Ni(OH)(2) suspensions on a glassy carbon electrode. At-1.0 V applied potential, 94.6% of TCE is reduced after 5 h of electrolysis. TCE is efficiently transformed to ethane at a wide pH range in simulated groundwater environment with low-conductivity. The air-exposed Ni(OH)(2) cathode can still dechlorinate 49.8% TCE, showing the antioxidative capacity of Ni(OH)(2 )cathode is superior than that of pristine Ni electrode. Both the directly transferred electrons and the generated atomic H* at the active Ni(0) sites contributed to the hydrodechlorination of TCE. Our work not only provides an effective way to completely detoxify chlorinated organic contaminants (COCs) under environment-relevant conditions, but also proves a concept that the chemical energy in COCs can be harvested during their electrochemical reduction processes.
查看更多>>摘要：Photocatalysis based advanced oxidation processes (AOPs) have drawn increasing attention for the removal of organic contaminants, while the relationships of the target organic contaminants with the intrinsic properties of the photocatalysts are usually neglected. Herein, the photocatalytic behaviors among ten kinds of organic contaminants and two heterojunction photocatalysts were comparatively investigated. Photocatalysts BiOCl0.75I0.25/g-C3N4 (BCI-CN) with abundant oxygen vacancies exhibited stronger absorption capacity towards light and quicker transfer efficiency of photoinduced carriers (factor eta 1x2) than BiOCl/g-C3N4 (BC-CN). Nevertheless, the redox ability (factor eta 3) of BCI-CN was weaker than that of BC-CN. Factor eta 1x2 and eta 3 synergistically and competitively affect the photocatalytic activities. Based on the differences and connections about intrinsic properties of BC(I)-CN photocatalysts, quantitative evaluation of structure-activity relationships among different organic contaminants and two photocatalysts were constructed, which provide valuable guidance for objectively evaluating the photocatalytic performance and precisely recognizing the compatibility among pollutants and photocatalysts.
查看更多>>摘要：Bimetallic catalysts tend to show excellent catalytic performance to activate peroxymonosulfate (PMS) due to the synergistic effect. Although the outstanding catalytic ability of metal silicates to activate PMS has been clarified for a long time, the synergistic effect and micro-mechanism of bimetal in silicate are still being ignored. In this work, we prepared Cu-doped cobalt silicate (CuCoSi) hollow nanospheres to confirm the synergistic effect of bimetal in silicate for activating PMS. A novel and comprehensive synergistic micro-mechanism at the molecular and electronic levels is proposed. Experimental and theoretical analysis reveals that Co provides unique active sites in CuCoSi and Cu enhances the radical pathway by electron transfer with Co instead of directly participating in the activation of PMS. The increased oxygen vacancies (Ov) in the material promotes the formation of O-1(2) due to Cu doping. This work lays a foundation of the development of bimetallic silicates catalysts.
查看更多>>摘要：Methane dehydroaromatization reaction at 700 degrees C over Mo/ZSM-5 involves numerous modifications of the molybdenum species from the catalyst preparation and throughout the catalyst lifetime, composed of 4 successive steps: calcination, activation, induction, and deactivation. A thorough kinetic study was undertaken with the aim to understand the transformation phenomena occurring on the catalyst during each stage of the reaction, using methane gas hourly space velocity per gram of catalyst (M-GHSV) from 1 to 29 L-CH4 h(-1) g(cat)(-1). Here from, unexpected behaviors were observed, supported by molecular modeling results. MoO3 firstly reacts stoichiometrically during the calcination (Delta rH=0.86 eV) with bridged hydroxyl pairs yielding [Mo2O5](2+) species (calcination). Thereafter, [Mo2O5](2+) slowly reduces by methane to form [Mo2C2](2+) (activation). The latter converts methane to ethylene (E-A = 1.49 eV), which dimerizes two times faster to butene through hydrocarbon pool catalysis rather than through Bronsted acid sites (induction). The catalyst deactivates through an inhibition effect of aromatics, which adsorb strongly onto [Mo2C2](2+) (Delta H-ads similar to 0.7 eV) (deactivation). The large amount of autogenous hydrogen produced at lower space velocity allows preventing the active species poisoning, leading to slower deactivation rate.
查看更多>>摘要：Styrene oxide is a pivotal organic intermediate in pharmaceuticals and fine chemicals synthesis. However, the current synthesis process relies on the use of peroxy acid or chlorohydrin, which is incompatible with establishing a more sustainable chemical industry. Here, we reported the synthesis of a quantum-sized SnO2 on 2D graphitic carbon nitride (CN) as a heterostructured catalyst, which displays efficient photocatalytic styrene epoxidation at room temperature using O-2 as a mild oxidant, achieving styrene conversion of 98.1% and styrene oxide yield of 71.8%. Photoelectrochemical analysis demonstrates efficient electron transferring exists from CN to SnO2, which enhances charge carriers' separation and transfer processes. Furthermore, we couple the photocatalytic styrene epoxidation with epoxide ring-opening amination, achieving the synthesis of value-added beta-amino alcohol in a cascade reaction fashion. This work may shed light on the heterostructured catalyst design for photocatalytic selective synthesis of valuable chemicals in a sustainable manner.
查看更多>>摘要：The SCR reaction on Cu-SSZ-13 is a redox process consisting of a reduction half-cycle (RHC) and an oxidation half-cycle (OHC). Despite extensive efforts to understand hydrothermal aging and sulfur poisoning, the impact of real-world aging on the SCR activity of Cu-SSZ-13 has not been reported. This work employs a transient response methodology consisting of experiments and kinetic models to investigate the SCR redox cycles at intra-catalyst locations of commercial Cu-SSZ-13 monolith catalysts in their degreened and real-world aged states, in the temperature range of 200-450 degrees C. Moreover, H2-TPR, NH3-TPD, SO2-TPD, ICP-OES and solid-state NMR were performed to investigate the catalyst properties. Sulfur aging and dealumination caused by real-world exposure decreased the reducible Cu density and SCR performance. Real-world aging was found to selectively slow OHC more than RHC, mainly due to lower mobility of the Cu ions coordinated to sulfur-related species leading to decreased formation of Cu-dimers necessary for OHC.
查看更多>>摘要：Herein, a feasible strategy was reported to reuse the waste ternary lithium-ion batteries (TLIBs) as precursors to develop efficient CoMnNiOx catalysts for propane oxidation. Interestingly, the T-90 value of the defect enhanced-CoMnNiOx catalyst for propane oxidation was only 200 degrees C. The de-aluminum and de-lithium process generated by the alkaline etching promoted the increase of the oxygen vacancy defects, which was confirmed by ICP-OES, XPS, EPR and DFT calculations. At the atomic level, the oxygen vacancies near the aluminum and lithium vacancies (NiO-Al-v-O-v and NiO-Li-v-O-v) were more likely to promote the activation of oxygen molecules. Furthermore, it was observed that the reducibility, acidity and lattice oxygen mobility of the defective CoMnNiOx catalyst were boosted by the presence of abundant oxygen vacancy defects, and thus enhancing the catalytic activity. Remarkably, the TLIBs recycling and defect enhancement engineering are conducive for the development of the green and efficient catalysts for VOCs oxidation.
查看更多>>摘要：Highly efficient platinum-group-metal (PGM) free catalysts for alkaline hydrogen oxidation reaction (HOR) are of vital issues for the development of alkaline hydroxide exchange membrane fuel cells (HEMFCs). Herein, with the help of interface engineering by the in-situ electrochemical surface reconfiguration strategy, the seamless nickel nitrides-nickel hydr(oxy)oxide (denoted as Ni3N-Ni(OH)(2)) heterostructures were developed. From the systematic electrochemical measurements, the impressive HOR performance such as nearly zero onset over-potential, larger exchange current density, excellent long-term durability, and robust CO tolerance in alkaline media, are obtained by the optimized Ni3N-Ni(OH)(2) catalyst, thus rendering it significant potential for applications in HEMFCs. Furthermore, this catalyst also exhibits superior HER activity, approaching to that of Pt/C catalyst. The tailored d band center of Ni and the enhanced hydroxyl adsorption ability at Ni3N-Ni(OH)(2) heterojunctions are evidenced by the comprehensive spectroscopy and electrochemical analyses, which are favor-able for the accelerated Volmer step toward alkaline hydrogen electrocatalysis.
查看更多>>摘要：Transformation of ethanol to more valuable C4+ alcohols by coupling reaction has been of great interest from the point of view of chemistry and technology of biomass utilization. This work reports atomic Ru on Mg and Al containing layered double oxides (MgAl-LDO) for ethanol coupling to C4+ alcohols. The atomic Ru remarkably promotes the coupling of ethanol, achieving a selectivity of 82.6% to C4+ alcohols under an ethanol conversion of 29.6%. Through tailoring Ru dispersion and acid-base properties, it has been found that atomic Ru promotes ethanol dehydrogenation and the following aldol condensation of acetaldehyde.
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