查看更多>>摘要：? 2022 Elsevier B.V.(La0.8Sr0.2)0.98MnO3-δ (LSM)- Zr0.92Y0.16O2-δ (YSZ) has been widely studied as the cathode for solid oxide fuel cells (SOFCs), but its low activity has been a cell performance limiting factor. Herein, LSM-YSZ:PrOx composite is developed as an active electrocatalyst for both oxygen reduction and evolution reactions. A single step PrOx infiltration into LSM-YSZ lowers the polarization resistance (Rp) 10–20 times depending on the test temperature. Distribution of relaxation times (DRT) calculation reveals that adding PrOx affects surface exchange between adsorbed/desorbed oxygen and lattice oxygen, and oxygen dissociative adsorption/desorption. A symmetrical cell with a thin YSZ electrolyte sandwiched between thick LSM-YSZ:PrOx electrode-supports is developed and its oxygen generation performance and stability are evaluated under various current densities and temperatures. Reversible solid oxide cell (ReSOC) performance is also reported for LSM-YSZ:PrOx supported cells with the oxide fuel electrode Sr0.95(Ti0.3Fe0.63Ni0.07)O3-δ (STFN).
查看更多>>摘要：? 2022 Elsevier B.V.The electrochemical CO2 reduction reaction (CO2RR) that transforms CO2 to CO has attracted great interest. Transition metal nanoparticles encapsulated in nitrogen-doped carbon (M@NC) catalysts exhibit outstanding catalytic performance. However, the role of metal and N species in M@NC catalysts remains unclear. In this work, Co@C, Co@NC, Ni@C, and Ni@NC catalysts were achieved and employed in CO2RR. The Ni@NC catalyst exhibits an industry level current density of 220 mA cm?2 and a high Faradaic efficiency of 98% for CO production at ? 0.87 V vs. RHE for 100 h. In addition, the N species, especially the pyrrolic-N in the shell of Ni@NC material provide active sites for adsorbing and activating CO2 molecules, and metal nanoparticles improve the electronic structure of N species, thereby decreasing their ability for radical attack (*COOH, *CO, and *H). Consequently, this work can guide the design of M@NC catalyst for CO2RR to CO.
查看更多>>摘要：? 2022Bimetal catalysis has been one of the major categories in heterogeneous catalysis field, and the efficient and durable catalysts can be well achieved by the bimetal synergy. Herein we report a remarkable achievement of both dehydrogenation activity of ammonia borane and durability by controllably engineering Pt-Ni interfacial sites via the Pt and the following NiO atomic layer deposition strategy, which can also realize the controllable synthesis of other Pt-M (M=Co, Cu, Fe and Zn) bimetal catalysts. Multiple characterization techniques, kinetic-isotopic analyses and density functional theory calculations were employed to unravel the nature of the Pt-Ni synergy. Experimental and theoretical results reveal that the decoration of nickel species on the Pt nanoparticles constructing the targeted Pt-Ni interfacial sites could lower the reaction activation energy, promote the adsorption, activation and dissociation of H2O molecules, and facilitate the desorption of hydrogen atoms, resulting in the doubly enhanced activity with a turnover frequency value of 751.6 molH2 molPt-1 min-1 and the remarkably improved durability. Our work offers an alternative and general strategy for the rational design of bimetal catalysts with specific interfacial structure and provides fundamental guidance for in-depth understanding of the bimetal synergy.
查看更多>>摘要：? 2022Isolated single atoms of a platinum-group dispersed in surface layer of a metal host to synthesize single-atom alloys (SAAs) has proven to be favorable for improving catalytic activity and while retaining high selectivity of host metal. Here we report a co-promotion strategy of PtCux single-atom alloy and copper-ceria interface for preferential oxidation of CO. The Pt0.1Cu0.19/CeO2 catalyst exhibits superior catalytic performance and excellent stability, attributable to the regulation of the electronic interaction between Pt and Cu as well as the high proportion of oxygen vacancies. Moreover, operando DRIFTS experiments prove that the partial of Cu0 on the surface of CeO2 is oxidized to Cu+ during catalysis. The adsorbed CO readily reacts with oxygen over the Pt0.1Cu0.19/CeO2 to produce CO2 due to the presence of two-type active sites. Density functional theory simulations in conjunction with isotopic experiments unequivocally reveal that the Mars-van Krevelen mechanism is prominent on the as-synthesized PtCu SAAs.
查看更多>>摘要：? 2022This study clarifies the effect of the nature of solid N-precursor molecules on the N-modification, more specifically unravels how solid N-precursors – here cyanamide and melamine - affect the physicochemical and catalytic properties of the resulting carbonsupports and final catalysts. Using such modified high surface area carbons, in situ measurements as humidity dependent performance, electrochemical surface area, proton resistivity and limiting current measurements were conducted to access the role and degree of ionomer coverage and transport resistances. Additional X-ray photoelectron spectroscopy (XPS) proves molecular interaction between acidic side chains and basic N-groups. Overall, we show the importance of the N-precursor and synthetic route determining which physicochemical parameter will be influenced in the resulting catalytic layer. Based on this, the pure presence of some N-moieties does not guarantee an improved ionomer distribution, but the modification process enables a tailoring effect of the carbon species itself affecting transport phenomena.
查看更多>>摘要：? 2022 Elsevier B.V.The low specific surface area, poor porosity, and weak charge transport caused by the disordered morphology of metal-N-site catalysts are the main factors limiting their environmental applications. Therefore, a hollow-nanotube carbon nitride (Cu-HNCN) catalyst with CuNx sites dispersed in a hollow nanotube-like CN was constructed and used for the degradation of organic pollutants via the photo-Fenton (PF) process. The high specific surface area, rich porosity, and good visible-light trapping capability of the Cu-HNCN nanotubes were identified. The Cu-HNCN/PF system achieved 96.0% degradation efficiency of tetracycline within 50 min and showed efficient degradation of various antibiotic contaminants. Moreover, the short Cu-N bonds contributed to the improved stability and decreased copper leaching in the Cu-HNCN/PF system. Cu-HNCN, with its enhanced photogenerated charge generation, separation, and transport, was the key to the generation of abundant active species and efficient degradation of pollutants. In addition, frontier electron density theory successfully distinguished the roles of different types of active species in the degradation process. This work provides new insights into the development of catalysts with high stability and accelerated electron transfer to enhance the application of the PF process in practical wastewater purification.
查看更多>>摘要：? 2022 Elsevier B.V.For industrial high-purity hydrogen production, it is essential to develop low-cost, earth-abundant, highly-efficient, and stable electrocatalysts which deliver high current density (j) at low overpotential (η) for oxygen evolution reaction (OER). Herein, we report an active mesoporous Ni2P @ FePOxHy pre-electrocatalyst, which delivers high j = 1 A cm?2 at η = 360 mV in 1 M KOH with long-term durability (12 days), fulfilling all the desirable commercial criteria for OER. The electrocatalyst shows abundant interfaces between crystalline metal phosphide and amorphous phosphorus-doped metal-oxide, improving charge transfer capability and providing access to rich electroactive sites. Combined with an excellent non-noble metal-based HER catalyst, we achieve commercially required j = 500/1000 mA cm?2 at 1.65/1.715 V for full water-splitting with excellent stability in highly corrosive alkaline environment (30% KOH). The alkaline-anion-exchange-membrane water-electrolyzer (AAEMWE) fabricated for commercial viability exhibits high j of 1 A cm?2 at 1.84 V with long-term durability as an economical hydrogen production method, outperforming the state-of-the-art Pt/C–IrO2 catalyst.
查看更多>>摘要：? 2022 Elsevier B.V.The SCR activity of MOx (M=Al, P, Si, Zr) promoted V2O5-WO3/TiO2 was investigated before and after sulfation. In situ IR spectroscopy indicated that the VOx active sites preferentially anchor on promoter generated surface hydroxyl. In situ Raman spectroscopy confirmed that all oxides are completely dispersed on the TiO2 surface. In situ NH3-IR spectroscopy showed that the oxides can increase the Lewis (AlOx and ZrOx) and Br?nsted (POx, SiOx, VOx, WOx and SOx) acid site concentrations. The SiOx and ZrOx promoters had little effect on NO conversion, while the AlOx and POx promoters and surface sulfation generally inhibited it. The SiOx promoted catalyst was highly SCR active despite lacking Lewis acid sites, indicating that they are not vital for SCR. The N2O formation activity of the catalyst was inhibited by surface sulfation and the promoters, correlating with the promoter and SOx induced increase in the Br?nsted acid sites’ strength.
查看更多>>摘要：? 2022 Elsevier B.V.The steam reforming of propane and LPG has been investigated over Ru, Rh, Ir, Pt, Pd and Re catalysts (1 wt%) dispersed on commercial metal oxide supports (Al2O3, TiO2, CeO2-ZrO2). The Ru and Rh catalysts exhibit higher activity, which is comparable to that of a reference 10%Ni/Al2O3 sample. The performance of the Al2O3-supported Rh and 10%Ni catalysts deteriorates with time-on-stream due to the deposition of polymeric (Cβ) and/or vermicular (CV) carbon. The Ru-containing catalysts are considerably more stable because of the formation of small amounts of easily gasified carbon. Best results were obtained for the Ru/CeO2-ZrO2 catalyst, which is characterized by high activity, high selectivity toward H2 and excellent stability with time-on-stream. This has been attributed to the formation of, mainly, monoatomic carbon (Cα) species under reaction conditions, the high efficiency of Ru to gasify carbon deposits, and the presence of labile lattice oxygen species on the CeO2-ZrO2 support.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, the photocatalytic chlorine-radical-mediated reaction dramatically enhanced the catalytic activity of TiO2 for ozone removal, which was different from traditional photocatalytic mechanism driven by hydroxyl radicals. Chlorinated TiO2 was prepared using the sol-gel method and modified through surface chlorination. The ozone-removal efficiency was up to 99.9% over the chlorinated TiO2 under UV light, which was 2.5 times that of bare TiO2. Moreover, experiments also showed that chlorinated TiO2 possessed excellent water-resistance and reusability. Characterization results unveiled that the chlorine is attached to the surface of TiO2 in the form of Ti–Cl bonds, which can capture holes to form·Cl. Subsequently, it was proven that the chain transfer reaction initiated by·Cl was mainly responsible for the remarkable improvement in the photocatalytic conversion of ozone. This new photocatalytic mechanism driven by chlorine radical opens up a new field of ozone removal by photocatalysis.
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