查看更多>>摘要：? 2022Atomic-scale metals as active center have been widely investigated for efficient photocatalysis. Understanding the specific electronic structure of atomic-scale center is of profound fundamental importance for superior catalytic performance. Here, we report an atomically dispersed gold on tungsten trioxide (Au1/WO3) catalyst for photocatalytic oxidation of methane toward value-added methanol. The Au1 species reveal a specific tip-enhanced local electrons field which favors the C-H dehydrogenation of methane and thus form methanol (up to 589 μmol g?1 h?1). Both experimental and theoretical results demonstrate such tip-enhanced effect enhance the catalytic activity of methane oxidation. The theoretical calculations further reveal a lower adsorption energy of product methanol on Au1, in contrast to Au particles, which suppresses the overoxidation of methanol, and thus promotes its selectivity. Establishing the relationship between electronic density and catalytic activity may create a platform for designing efficient atomic-scale catalysts for C1 catalysis and green chemistry.
查看更多>>摘要：? 2022 Elsevier B.V.Alkaline exchange membrane fuel cells are impeded by the lack of cost-effective, highly efficient catalysts for the sluggish hydrogen oxidation reaction (HOR). Herein, single-atomic Pd sites supported by ordered porous N,S-doped carbon are synthesized, exhibiting remarkable alkaline HOR performance. This catalyst exhibits an ultrahigh anodic current density and mass-specific kinetic current of 2.01 mA cm–2 and 27,719 A gPd–1 (at an overpotential of 50 mV), respectively, not only outperforming the Pt/C counterpart but also making it among the best reported HOR catalysts. Furthermore, this catalyst exhibits a negligible activity decay during long-term electrolysis and a good CO tolerance capability. Experiments and theoretical calculations indicate that the synergistic effect from single Pd sites and heteroatom doping (N and S) weakens the binding energy of Had intermediates, thereby accounting for its superior HOR activity. This study provides a guideline for developing single-atomic site catalysts for highly efficient, stable alkaline HOR.
查看更多>>摘要：? 2022 Elsevier B.V.A heterogeneous Pd catalyst, biologically-mineralized palladium nanoparticles (bio-Pd), was synthesized using sulfidogenic bacteria which reduced soluble Pd(II) to catalytically-active Pd-nanoparticles (NPs). Heat treatment (processing) of bio-Pd (5 or 20 wt% on the cells) made by Desulfovibrio desulfuricans evolved supported Pd-catalyst comprising Pd-NPs held on large spherical hollow structures. The rate of hydrogenation of 2-butyne-1,4-diol was ~5-fold slower than for a commercial catalyst (~twice that of native bio-Pd), but with high selectivity to the alkene, fulfilling a key industrial criterion. In the Heck reaction, while bio-Pd showed a comparable reaction rate in ethyl cinnamate synthesis to that achieved by commercial Pd/C, heat-treated bio-Pd had negligible activity. D. desulfuricans bio-Pd was replaced by bio-Pd made using a consortium of waste acidophilic sulfidogenic bacteria (CAS) supplied from an unrelated primary remediation process. This gave comparable activity to commercial 5 wt% Pd/C in ethyl cinnamate synthesis, signposting an economic, scalable route to catalyst manufacture.
查看更多>>摘要：? 2022 Elsevier B.V.NiAl-LDH (NALDH) nanosheets were in intimate contact with g-C3N4 (CN) nanosheets to form ultratight sheet-sheet heterojunctions, which interweaved into network framework with introduction of the graphene aerogel (GA). Notably, the NALDH/CN/GA-20 showed a remarkable CO production rate of 28.83 μmol·g?1·h?1 under visible light irradiation, which was 24 and 16 times those of pure NALDH and bare CN, respectively. Furthermore, it was far exceeding the reported conventional CO2 photocatalytic reduction efficiency. The ultratight sheet-sheet heterojunctions not only shorten the charge transmission distance, but result abundant active sites and coupling large interfaces. The unique structure promoted the transport and separation of photogenerated carriers, and facilitated effective mass transport and light absorption. Multi electron series reduction mechanism based on type-II photocatalytic system was proposed to explain the CO2 reduction pathway. This work provides insight for designing photocatalysts with ideal performance for CO2 reduction.
查看更多>>摘要：? 2022 Elsevier B.V.Nickel-based cermet anode-supported protonic ceramic fuel cells (PCFCs) show great potential for direct utilization of ammonia. However, the insufficient activity of anode and the deterioration of anode activity/durability caused by the undesired interaction between nickel and ammonia greatly limit the application. Here, we report tubular PCFCs embedded with a catalytic iron layer. Such cells show peak power densities of 1.507 W cm-2 and 1.078 W cm-2 at 700 °C when using H2 and NH3 as fuel, respectively, which are the highest tubular PCFC performance so far ever reported. In addition, the stability of cells with the catalyst layer has been dramatically enhanced when compared with that of cells without the catalyst layer. The enhancement of activity and durability is attributed to the catalytic activity of iron for ammonia decomposition, through which the direct contact between nickel and ammonia has been minimized and the anode structure has therefore been protected.
查看更多>>摘要：? 2022 Elsevier B.V.Efficient aromatic alcohol oxidation with simultaneous H2 evolution under aqueous conditions is achieved in a polyoxometalate (POM)-incorporated ZnIn2S4 dual-functional photocatalytic system. The synergy between HPM and ZIS contributes to the formation of a Z-type heterojunction structure and thus enhances redox capacity. Moreover, the sub-nanometer size of POM clusters endows molecular-level interfacial contact, which acts as an “electron bridge” ensuring faster interfacial charge transfer kinetics. Therefore, an impressive nearly 100% yield of benzaldehyde and 10.6 mmol·g?1·h?1 H2-evolution rate are observed for POM/ZIS nanocomposites even under an anaerobic atmosphere with water as the solvent. This is the first application of POM-based materials in the anaerobic oxidation of benzyl alcohol with concomitant H2 production. This study expands the possibilities for designing multifunctional POM-based photocatalysts for economic and ecological photoredox applications.
查看更多>>摘要：? 2022 Elsevier B.V.Catalysts play a vital role in electrochemical reduction of CO2 to valuable products. Only based on effective catalysts, CO2 electrolysis process can be advanced toward industrial application. In this work, we present a Sb-Cu2O material synthesized via one-pot microwave-assisted solvothermal route. The Sb-Cu2O derived bimetallic catalyst achieves a highest CO selectivity of 96% and good CO partial current densities of 37.3 and 74.0 mA cm?2 at ? 0.8 and ? 1.2 V vs. reversible hydrogen electrode (RHE), respectively. The Sb-Cu catalyst also displays good stability at current densities ranging from 5.6 to 100 mA cm?2. Additionally, for the first time, a complete theoretical study reveals the critical roles of Sb in selective CO2 conversion to CO on this bimetallic material, including stabilizing stepped Cu surfaces selective for the reaction, lowering energy barriers for the formation of key intermediate and favouring CO desorption.
查看更多>>摘要：? 2022 Elsevier B.V.Organic polymer materials as a promising type of photocatalyst are still limited by the poor transport efficiency of photoinduced carrier. Herein, a series of cross-linked ultrathin polyphosphazene-based nanosheets is developed by regulating the N-containing skeleton. The aromatic ring, pyrimidine ring and s-triazine ring are bonded with cyclotriphosphazene to form large-sized 2D nanosheets, respectively. Experimental results and theoretical calculations have determined the pyrimidine ring that has a stronger ability to adsorb CO2 and can provide a suitable band gap and a stronger built-in electric field, so as to realize the rapid separation of photoproduced carrier. 2PC sample with the pyrimidine ring delivered near 100% selectivity for CO2-to-CH4 conversion with an impressive rate of 626 μmol g?1 without cocatalyst and photosensitizer under visible light illumination, surpassing many reported photocatalysts. Briefly, this work offers a fresh means for the construction of high-performance polymers by regulating the internal framework.
查看更多>>摘要：? 2022 Elsevier B.V.Developing an ultraefficient heterogeneous catalyst for peroxymonosulfate (PMS) activation at a wide pH range is a challenge. Herein, ultrathin NiCo2O4 nanosheets (NiCo2O4NS, ~1 nm), with the dominant exposure of (311) facet, was designed for PMS activation. The NiCo2O4NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range. The synergistic effects between Ni and Co were the dominant activation mechanism. Compared with Co3O4, NiCo2O4NS adsorb PMS through a unique “bridge” mode, where both Co and adjacent Ni interact with the same O atom in PMS, increasing the number of electron transfer for enhanced breakage of O[sbnd]O bond. NiCo2O4NS with high cycling stability, could reach 100% degradation of other typical pollutants, and showed higher degradation performance in actual wastewater. This work unveils the intrinsic origin of the superior activity of Co-Ni spinel oxides for PMS activation for the first time, and demonstrates its application potential for organic contaminants degradation.
查看更多>>摘要：? 2022Nano-structured metal cocatalysts are easy to be oxidized and form mixed valences and interfaces which would facilitate the catalytic performance in previous studies. Herein, as an example in photocatalysis, three kinds of Pd cocatalysts with various valence distributions (PdO70-Pd30/CN, PdO50-Pd50/CN and PdO30-Pd70/CN) were loaded on g-C3N4 nanosheets with the close loading amounts (~1 wt%) and uniform sizes (2–3 nm). Then, the results of the photocatalytic degradation of ciprofloxacin showed that the generated oxidative active species are highly related to the distribution of palladium valence. Pd2+ (PdO) benefits the production of·O2-, while Pd0 benefits the production of h+. The theoretical simulations revealed that surface states e.g., electron distribution and the adsorption ability of O2 on different Pd species determined the production of·O2- and h+. Besides, PdO50-Pd50/CN showed the best performance for degrading ciprofloxacin, due to the joint action of·O2- and h+ in the CIP degradation.
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