查看更多>>摘要：? 2022 Elsevier B.V.Appropriate adsorption strength and modes of intermediates on catalysts and the reaction kinetic energy barrier directly determine the selectivity and productivity of final products during CO2 electroreduction. This work systematically reveals the mechanisms for enhanced CO2 electroreduction on nitrogen-doped Cu2O (N-Cu2O) catalyst by in-situ surface enhanced Raman spectroscopy (SERS) and theoretical calculation. The introduction of N into Cu2O can significantly enhance the CO2 adsorption capacity, binding strength of key intermediates and increase the local pH value, resulting in two-fold enhancement of CO and C2H4 production as compared to bare Cu2O. Meanwhile, the protonation step is promoted, making the formation of COOH· quickly and earlier. Therefore, the adsorbed CO2·- intermediate formation is produced more rapidly, and the rate-determining step is transferred, continually facilitating the electroreduction of CO2. This study is inspiring in designing high-performance electrocatalysts for CO2 reduction.
查看更多>>摘要：? 2022 Elsevier B.V.Dual-atomic-site catalysts (DASCs), as an extension of single-atom catalysts (SACs), have attracted increasing attention owing to the synergistic effect. However, the study of DASCs is still at the early stages and mainly based on metal atom pairs. More experimental and theoretical exploration needed for further guiding the reasonable design of diatomic active sites. Herein, remarkable activity for oxygen reduction reaction (ORR) of Se1-NC single-atom catalyst was discovered, and then Fe/Se dual-atom catalysts were constructed to demonstrate the dual-atom sites synergistic effect. Encouraging, the Fe1Se1-NC catalyst displays significant enhancement for ORR towards Fe1-NC and Se1-NC in both alkaline and acid electrolytes. Spectroscopic characterizations and theoretical calculations reveal that there are multiple effects for the introduction of Se, especially for supplying new active sites, and effectively tuning charge redistribution and the spin-state of Fe active sites, which presenting a new strategy to improve the electrochemical performance based on the metal-nonmetal dual-atomic-site catalysts.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, ZnCoOx catalysts were prepared using in situ pyrolysis of ZnCo bimetallic zeolitic imidazolate frameworks (ZIFs), which were rationally designed on the basis of a metal ion doping strategy. The derived Zn0.05CoOx with proper doping of Zn (Zn/Co molar ratio of 0.05) exhibited superior catalytic activity and durability towards catalytic elimination of different volatile organic compounds (VOCs) including benzene, toluene and cyclohexane under simulated real-exhaust conditions. Both Br?nsted and Lewis acid sites were beneficial for cyclohexane degradation, whereas only Lewis acid sites were responsible for eliminations of benzene and toluene. In addition, the effect of chemical structures of VOCs on their catalytic elimination over Zn0.05CoOx was explored. Compared to benzene and toluene, cyclohexane molecule was more easily eliminated, attributed to strong adsorption onto catalyst and special chemical structure of cyclohexane. The obtained results can provide new strategy for rational design of highly efficient catalytic materials for eliminating VOCs.
查看更多>>摘要：? 2022 Elsevier B.V.Producing green hydrogen efficiently via proton exchange membrane water electrolysis (PEMWE) is the key for achieving decarbonization targets. Iridium catalyst is expensive, and it is important to minimize its use and to optimize interface between Ir and ionomer or water for higher utilization of catalyst in oxygen evolution reaction. In this paper, x-ray computed tomography along with electrochemical and modeling techniques are used to characterize the interface for two different porous transport layers (PTLs) and catalyst layers at various loadings. We show that low porosity sintered PTLs exhibit higher interfacial contact with the catalyst and the membrane that results in improved kinetics. Radiography and modeling results indicate that oxygen taking multiple transport pathways through the PTL results in slug flow through the channels that reduces mass transport overpotential. Based on the results, we suggest design guidelines for high efficiency and durable PEMWE and their components.
查看更多>>摘要：? 2022 Elsevier B.V.Antibiotics (or pharmaceuticals) and inorganic nitrogen may coexist in mariculture wastewater, adversely affecting food safety and coastal ecology. Advanced treatment of marine wastewater is of great significance. In this study, simultaneous removal of refractory berberine chloride (BC) and ammonium nitrogen (NH4+-N) was firstly achieved in a visible-light-driven marine photocatalytic fuel cell/peroxymonosulfate (PFC/PMS) system. The modified blue TiO2 nanotube arrays (TNA) anode and Cu-Co-WO3 cathode bridged photo-electrocatalysis, sulfate radical-based oxidation and catalytic chlorination, benefiting both pollutant removal and fuel cell electricity generation. Under optimized conditions (double photoelectrodes, 2.5 mM PMS, R = 500 Ω), the system had an open circuit voltage of 0.57 V, removing 95% of BC and NH4+-N, meeting the discharge standard of mariculture. Natural-sourced CODMn, and inorganic nitrogen in simulated mariculture wastewater were also efficiently removed with power generation. The mechanism involving (photo-)electrocatalytic chlorination and PMS-chlorination theoretically supports the application/optimization of integrated electrochemical technologies for marine pollution control.
查看更多>>摘要：? 2022 Elsevier B.V.Limited light absorption and low charge separation rate are the main obstacles for graphitic carbon nitride (g-C3N4)-based photocatalyst. Here, onion-liked carbon (OLC), a carbon nanostructure with multilayer graphitic shells, was embedded into the g-C3N4 matrix to enhance the photocatalytic performance. Due to its high degree of sp2 hybridization and good electrical conductivity, the OLC can broaden visible light adsorption, narrow the band gap of g-C3N4, and serve as electron acceptor to promote the separation of photo-generated carrier. Thus, the g-C3N4/OLC composites show an increased hydrogen evolution rate of 3086 μmol g?1 h?1, 4.44 times higher than pure g-C3N4. Furthermore, the H2 evolution rate is highly related to the sp2/sp3 ratio of OLC. In addition, efficient photocatalytic degradation of RhB was also achieved (0.1171 min?1). The photocatalytic mechanism was then elucidated through a series of spectrochemical and photochemical test. This work demonstrates the significant applicability of OLC in designing carbon-based photocatalyst with highly-efficient photocatalytic activity towards future solar energy conversion and pollutants degeneration.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, we investigated the nitrate photolysis on photoactive TiO2 particles in the presence of SO2 through theoretic DFT calculation and in situ DRIFTS analysis, and found that in a clean atmosphere nitrate was oxidized to ?NO3 radicals by the holes generated on the surface of TiO2 under solar irradiation, followed reactive nitrogen species generation via ?NO3 radicals reduction by photoinduced electrons. After shifting to the SO2-polluted environment, ?NO3 radicals preferentially reacted with abundant sulfites to significantly increase nitrogen species formation, the online measured concentrations of NOx and HONO increased by approximately 2-fold and 6-fold respectively in comparison with clean atmosphere. These results demonstrate that photogenerated holes play a key role in nitrate photolysis on photoactive mineral dusts with or without the coexistence of SO2, providing new insights into the source of NOx and HONO in complex air polluted areas during the daytime.
查看更多>>摘要：? 2022 Elsevier B.V.Mechanistic understanding of the effect of electron transfer rate across the semiconductor heterojunction interface on its photocatalytic activity remains elusive. Herein, a series of sensitized semiconductor heterojunctions consisting of monodisperse CdS quantum dots (QDs) with controllable sizes range of 2.2–6.5 nm and cadmium tetrakis(4-carboxyphenyl)porphyrin (Cd-TCPP) nanosheets are constructed through partial sulfidation strategy. The in situ resultant CdS/Cd-TCPP composites exhibit size-dependent photocatalytic hydrogen evolution reaction (HER) activity with the highest activity of 3150 μmol·h?1·g?1 obtained at a medium CdS QD size of 4.8 nm. It is demonstrated that the interfacial electron transfer rate and the corresponding photocatalytic HER activity can be regulated by tuning the CdS QD size that determines the conduction band position of CdS relative to Cd-TCPP. This work provides a new strategy that rationally controls the interfacial electron transfer rate for developing highly efficient photocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.Synthesis gas (syngas), with a wide range of molar ratios of CO and H2 from 0.3 to 4, can serve as an important feedstock in the petroleum industry for the production of various synfuels; however, it remains a major challenge to tune the composition over such a wide range of ratios. Here, we demonstrate the photocatalytic production of syngas with tunable H2/CO molar ratios via rationally designed Au/MoS2 symmetrically tipped CdS nanowires (AMTCs), in which MoS2 and Au serve as cocatalysts for the hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR), respectively. The competing reactions are controlled and aligned through the selective decoration of size-controlled (1–50 nm) Au nanoparticles on MoS2 by controlling the charge transfer kinetics during photodeposition. Finally, the widest range of H2/CO ratios in syngas reported to date, ranging from 0.35 to 3.6, is realized, indicating that this is a potentially efficient approach for solar-to-syngas production by using rationally designed nanostructures.
查看更多>>摘要：? 2022 Elsevier B.V.Fe-N-C catalysts are promising alternatives to the platinum-group catalysts for use in oxygen reduction reactions of proton exchange membrane fuel cells. However, Fe-N-C catalysts suffer from poor durability, compared to non-precious metal catalysts, because of their accelerated demetallation by the Fenton reaction. In this study, we report the synthesis of a melamine-encapsulated Co-ZnO-C composite as a precursor and template for zeolite-imidazole-frameworks (ZIF-8). This approach allows formation of Co-N-C for constructing unique structures at meso- and macropore scales, while maintaining microporosity. Density functional theory analysis confirms the superior stability of the Co-N-C catalyst over other M-N-C catalysts (M = Fe, Ni, Cr, and Mn). Furthermore, it reveals that a closed interaction between the Co-N4 moiety and organic adducts enhances oxophilicity, which prefers a 4-electron ORR activity. The Co-NC catalyst with a developed pore structure shows remarkable durability (6.7% performance degradation for 100 h) and full cell performance in H2/O2 under 1 bar of backpressure (723 mW/cm2 of maximum power density). Consequently, the unique structure of the synthesized catalyst successfully translates to the computationally-established ORR activity in the half-cell; superior durability is seen in the real device operation and stability analysis. This work is expected to support next-generation fuel cell development.
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