查看更多>>摘要：Catalytic combustion (CC) and chemical looping combustion (CLC) are promising technologies for energy saving and emission reduction of CO2 in treatment of steelmaking off-gas. This work firstly reports and compares the evolution behavior and quantitative reaction mechanisms of cube Cu2O model catalyst for CC and CLC reactions. The Cu2O-CC exhibited the higher activity and stability than Cu2O-CLC. The typical characterization results suggested that the only surface unstable Cu2O was oxidized to CuO, and the excellent synergistic effect of metal-oxide interface (100) between Cu~+/Cu~(2+) and active lattice oxygen species for Cu2O-CC reaction. But, for CLC reaction, Cu2O structure was collapsed, which caused the agglomeration of CuOx species and gradual decrease of reaction stability. Three different active oxygen species (surface cycle lattice oxygen, bulk lattice oxygen, and adsorbed oxygen) and the detailed reaction pathways were proposed by the in situ IR spectroscopy, isotopic (~(18)O2) transient exchange experiments and DFT simulation. The intrinsic activity of surface cycle lattice oxygen was higher in terms of TOF (13.5 × 10~(-3) s~(-1)) and facile formation of C~(16)O~(18)O on the cubic interface of Cu2O-CC through adsorbed CO during CC process. The contribution degrees of Mars-van-Krevelen (M-K) and Lang-muir-Hinshelwood (L-H) mechanisms for CC and CLC reactions were 76.6% and 23.4% for CC, and 89.7% and 10.3% for CLC on Cu2O catalyst, respectively.
查看更多>>摘要：A stable and high-efficiency bamboo-inspired catalytic capillary microreactor (CMR) decorated with Ag nano-particles (NPs) is skillfully designed for the continuous-flow reduction of nitroaromatics. By a novel continuous-flow method, Ag NPs are mainly dispersed around the long microchannels uniformly and firmly in bamboo vascular bundle. The bioinspired CMR achieves a continuously effective fluid flow while maintaining the high reactivity of Ag catalyst in the reduction of four nitroaromatics and shows good long-term stability where the catalytic performance remained at 90% within 11 h of five cycles. The detection of H* radical adducts indicated that Ag NPs adsorb the BH4~- ions to form the Ag-H species. The exceptional pore channel of CMR with a large surface area provides active sites readily accessible and facilitates H* radicals and electrons transfer to sinafi-cantly enhance nitroaromatic reduction. This sustainable bamboo-inspired design can greatly impel the future development of renewable catalysis system for wider applications.
查看更多>>摘要：The water contaminant control with the simultaneous production of clean energy has been considered an ideal and sustainable strategy. Herein, a self-assembled Zn2In2S5 with N-doped hollow carbon spheres (NHCS) was first synthesized via in-situ hydrothermal method to achieve excellent performance for aromatic pollutant removal with high amounts of H2O2 formed. Such a composite harvested phenol degradation efficiency of 97.6% with high H2O2 yield of 1.31 mmol L~(-1), and bisphenol A (BPA) degradation efficiency of 79.7% with high H2O2 yield of 2.31 mmol L~(-1). In addition, in-situ produced H2O2 solution of composites achieved high-efficiency bacterial inactivation. Based on the characterization results, NHCS contained abundant aromatic frameworks of % conjugates with C-C and N-hybrid rings. Meanwhile, phenol or BPA with rich z bonds was tightly adsorbed to the photocatalyst surface through π-π interactions, which resulted in decreased activation energy with surface-adsorbed phenol */BPA * . The obtained electrons were quickly transferred to the dispersed dissolved oxygen accompanied by promoting the reduction of O2 into H2O2. This synergetic process was expected to develop novel photocatalysts towards water disinfection achieved the reuse of wastewater.
查看更多>>摘要：In this work, visible light total reflective SiO2 @TiO2 core-shell catalyst was synthesized by atomic layer deposition (ALD). This core-shell catalyst processing a total reflection character against full visible light favors the total effective traveling length of visible light inside the TiO2 shell. Subsequently, higher catalyst temperature under visible light irradiation expands the light absorbing window of amorphous TiO2 to full visible light due to its negative temperature coefficient of the forbidden bandwidth. Boosted photothermal conversion efficiency (145% that of amorphous TiO2) can be achieved to exhibit a 17β-estrogen degradation rate 1.5 times that of the commercial P25 (a mixed TiO2 crystal of 20% rutile and 80% anatase) and 2.9 times catalytic velocity that of P25. The boosted catalytic performance of SiO2 @TiO2 core-shell catalyst is attributed by expanded visible-light absorption, boosted photothermal conversion efficiency, and prolonged carrier lifetime.
查看更多>>摘要：Development of efficient and stable catalyst for the degradation of chlorinated volatile organic compounds (VOCs) is a hot research topic. In this study, we used plastic-based terephthalic acid for the synthesis of MIL-125, which further modified by the -NH2 and -NO2 groups. DFT calculations revealed that the N orbitals had an important contribution in reducing the band gap, leading to easier hydrogen absorption and high electron transfer efficiency. Optical studies, XPS, TRES, NH3-TPD and pyridine IR further demonstrated mat the amino modification promoted the visible absorption range and acidity of MIL-125 in comparison to the nitro modification, resulting in efficient catalytic degradation of chlorobenzene and toluene, even in the presence of water. This work provides an economically feasible strategy for modifying metal organic frameworks (MOFs) and suggests the possible VOCs degradation pathways with EPR, in situ FTIR, GC-MS and TG-MS analysis.
查看更多>>摘要：Oxygen evolution reaction (OER) impedes the electrochemical water splitting for H2 production primarily because of the sluggish kinetics. Cobalt oxides with abundant oxygen vacancies (Vos) have been proved to be the promising OER electrocatalysts showing high catalytic performance. However, precisely controlling the concentration of the Vos and large-scale synthesis of these electrocatalysts are still not resolved. Herein, we propose an ε-beam evaporation alloy-UV/O3 oxidation method for fabricating optically transparent alloy oxide films (f-Ni_(0.1)Co_(0.9)Ox) only 10 nm thick. The concentration of the oxygen vacancies is positive correlated with the Ni content in the alloy oxides. The optimum binary Ni/Co (1/9) alloy oxide with the best defect O/lattice O ratio (0.952) exhibits ultrahigh OER mass activity of 3055 A g~(-1) at 250 mV overpotential in 1.0 M KOH, almost 7.5 times and 190 times as high as CoOx and the commercial benchmark RuO2 OER catalysts, respectively. Moreover, directly depositing f-Ni_(0.1)Co_(0.9)Ox film on the top of the tandem-junction a-Si PV cell realizes wireless unassisted solar-driven water splitting with high solar-to-hydrogen conversion efficiency. The key roles of modulating the electron structure, stably reversible spinel structure and the reaction barrier reduction were revealed in situ spectroscopy and density functional theory calculations. This study provides a new perspective of oxygen vacancy modulation for high electrocatalysis performance via large-scale synthesis of such bimetallic alloy oxides.
查看更多>>摘要：Currently, inner-generate hydrogen peroxide to enhance the degradation of pollutants is an outstanding way. However, few studies have been done on MoS2 photocatalysts with sulfur vacancies at the phase-junction to produce innergenerate-H2O2 to promote contaminants degradation. Herein, we prepared Mo_(1-x)S_(2-y) photo-catalysts with sulfur vacancies at the phase-junction by a simple method (temperature-programmed reduction in hydrogen atmosphere) to achieve high innergenerate-H2O2 and high degradation efficiency. Specifically, Mo_(1-x)S_(2-y) exhibited a high yield of innergenerate-H2O2 (35 nmol L~(-1) h~(-1),1.5 times as high as bulk MoS2) under simulated solar irradiation, because the promoted electron transfer can increase superoxide radical to generate innergenerate-H2O2. Hydroxyl radicals generated by decomposition of innergenerate-H2O2 through the transformation of variable metal molybdenum atom (Mo(IV)/Mo(VI)) can effectively improve the degradation efficiency of tetracycline and diclofenac sodium (twice as high as bulk M0S2). The novel and concise way was paved to synthesize photocatalysts for high-efficiency photocatalytic degradation by innergenerate-H2O2.
查看更多>>摘要：A series of layered Co-Al-O catalysts derived from hydrotalcites for low-temperature CO2 methanation were prepared via a hydrothermal method and reduced at 500, 550, 600, 650, and 700 ℃, respectively. The characterisation results from XPS and CO2-TPD revealed that the Co~0 content and basic sites over these catalysts were firstly increased and then decreased with the reduction temperature increasing, which led to the efficient dissociation of H2 and CO2 adsorption. In situ DRIFTS measurements revealed that the formation of CH4 proceeded via the hydrogenation of carbonate and formate as intermediates. A superior catalytic performance of Co-Al-O-600 catalyst for CO2 methanation was achieved with a CO2 conversion of 74% and a CH4 selectivity of 99% at low temperature of 250 °C. Moreover, it exhibited excellent resistance to coking and sintering upon a 240 h time on stream operation.
查看更多>>摘要：A novel material with N-doped carbon dots decorated three-dimensional graphitic carbon nitride (NCDs/TCN) is synthesized using NaCl as template. Abundant Na~+ are found to be in-situ doped in 3D g-C3N4 framework. Experiments and density functional theory (DFT) calculations suggest that peroxydisulfate (PDS) activation follows radical and non-radical pathways on the NCDs/TCN catalyst. NCDs have superior up-conversion pho-toluminescence property and can enhance charge separation efficiency, thus improving the photocatalytic reactivity of 3D g-C3N4 and promoting the radical activation of PDS efficiently. Interestingly, the NCDs/TCN-PDS* complex can be formed due to the large adsorption energy of doped Na~+ for PDS, thus inducing the non-radical PDS activation pathway. This work provides an effective approach to combine radical and nonradical pathways for boosting PDS activation and gives deep insights for the non-radical pathway induced by doped Na~+ in 3D g-C3N4.
查看更多>>摘要：The oxygen reduction reaction (ORR) is essential for both energy conversion devices and green hydrogen peroxide (H2O2) synthesis. Whereas, it remains a challenge to efficiently tune the oxygen reduction selectivity toward the target applications. Herein, we designed two kinds of Co-N-C materials with encapsulated Co nanoparticles (Co_(NP)-N-C) and with atomically dispersed cobalt atoms strongly embedded into nitrogen-doped carbon nanotubes (Co_(SA)-N-CNTs), and successfully realized the ORR pathway transformation from four-electron (4e~-) to two-electron (2e~-) for high-performance H2O2 production. This tunability is ascribed to the modification of the atomic configuration of the Co-N-C catalyst. Remarkably, when employing Cosa-N-CNTs material as a 2e~- ORR catalyst, the assembled electrode exhibits a high H2O2 production rate of approximately 974 ± 25 mmol g_(cat)~(-1) h~(-1), along with an ultra-fast organic matter degradation performance. This work provides an efficient strategy for tuning oxygen reduction selectivity via a simple structure tuning of the materials for specific applications.
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