查看更多>>摘要：Electrolysis in seawater is cost-saving but challenging approach for hydrogen production. In this study, self-supported anticaustic three dimensional (3D) microcolumns anchored with trace Pt clusters on nickel foam (NF) is prepared through solvothermal followed by thermal reduction procedures (Pt-Co-Mo). The as-synthesized electrode owns superhydrophilic and aerophilic surface which favors close contact between the electrode and electrolyte and release of the generated hydrogen bubbles. Besides, the strong synergistic effect between Pt and matrix lead to a significantly improved HER intrinsic activity. Thanks to the above merits, the self-supported Pt-Co-Mo electrode presents outstanding HER activity, which only requires an extremely low overpotentials of 179.2 mV and 194.1 mV to reach a large current density of 2000 mA cm~(-2) in 1 M KOH and 1 M KOH seawater, respectively. For overall water splitting, cell voltages down to 1.50 V and 1.51 V are necessary to drive 10 mA cm~(-2) in 1 M KOH and alkaline seawater, respectively.
查看更多>>摘要：Hydrogen sulfide (H2S) is one of the most harmful pollutants to human health and the environment. Using carbon-based catalysts, H2S can be selectively oxidized to elemental sulfur (S) at room temperature and carbon-sulfur composites are produced, which enlightens a facile solution combining desulfurization with cathode preparation for high-performance hthium-sulfur batteries (LSBs). Herein, a heterogeneous catalyst of cobalt decorated N-doped hollow carbon nanofibers (Co-NHCFs) is designed for realizing the integrated application, in which the electron redistribution arising from long-range interactions of Co/N-doped carbon significantly promotes the oxygen radical generation and H2S dissociation, leading to its robust catalytic activity for H2S oxidation. Benefiting from the hollow framework with capacious storage space for rapid gas diffusion, the in-situ fabrication of high S-loading carbon-based cathodes (S@Co-NHCFs) used for LSBs is achieved during the H2S oxidation processing. Due to the more favorable diffusion of H2S gas than liquid S, this kind of chemical reaction-induced deposition can realize a more uniform distribution of solid S upon carbon than the traditional method by molten infusion, which, coupled with the catalysis of heterogeneous effect on the reversible sulfur-redox reaction, results in superior electrochemical performance of S@Co-NHCFs in LSBs.
查看更多>>摘要：A flexible air electrode with excellent activity and outstanding stability is highly desirable for metal-air batteries. Herein, the rational design of CoNi alloys derived intertwined N-doped carbon nanotube arrays onto carbon cloth (CoNi@NCNTs/CC) is reported, as self-supported air electrodes for flexible zinc-air and aluminum-air batteries. CoNi@NCNTs/CC exhibits a low potential of 1.56 V at 10 mA cm~(-2) in OER, along with a half-wave potential of 0.82 V in ORR, which is attributed to abundant active sites including CoNi alloys with optimized adsorption energy, Co/Ni-Nx and N-doped CNTs. The well-designed nanotube array construction with substantial channels on carbon cloth facilitates the mass diffusion and electron delivery, and improves mechanical flexibility. Combining excellent activity and promising flexibility, CoNi@NCNTs/CC based liquid- and all-solid-state zinc-air batteries exhibit excellent charge/discharge capability and long-term stability. And the liquid- and all-solid-state aluminum-air batteries deliver promising discharge property with a high open circuit voltage as well as commendable flexibility.
查看更多>>摘要：Exploiting inexhaustible free energy from the sun to produce clean and sustainable fuels is an attractive route toward the heavily polluted earth and energy shortage. Photoelectrochemical cell is strategic energy device because the generated fuels can be stored and used on-demand. Herein, we present the fabrication of Si photoelectrodes with efficient charge separation and transfer using metal-insulator-semiconductor heterostructures for energy-rich fuel production via photoelectrochemical water and urea oxidation. With controls of the native SiOx insulator layer and catalytic NiFe metal layer, Si photoelectrode exhibits a photovoltage of 530 mV and a photocurrent density of 33.3 mA cm~(-2) at 1.23 V versus reversible hydrogen electrode. Further employed Ni(OH)2 catalysts allow Si photoanode to achieve fill factor of 25.73% and solar-to-hydrogen conversion efficiency of 10.8% with a perovskite/Si tandem solar cell. The fabricated Ni(OH)2/NiFe/n-Si photoanode shows considerable performances toward urea oxidation. Our work presents new insights into sunlight-assisted hydrogen production using wastewater.
查看更多>>摘要：In the preparation process of carbon-based transition metal catalysts, the transition metal atoms usually seriously agglomerate, thus reducing the catalytic activity. To slow down the agglomeration of transition metal atoms during high-temperature treatments, herein, organics with coordination functions are proposed to regulate the typical metal-organic framework compound ZIF-67 with rich Co atoms. Electron microscopy structural characterization proves that ZIF-67 modified by coordinated organic compounds, including ascorbic acid (AA), citric acid (CA) and ethylene diamine tetraace tic acid disodium salt (EA), greatly improves the dispersibility of cobalt in the final product. All the adjusted ZIF-67 can derive cobalt-based bifunctional oxygen catalysts with higher activity. Among them, EA-MOF-Co shows the best ORR performance, with a half-wave potential comparable to commercial Pt/C in alkaline solutions and an obviously reduced oxygen evolution overpotential. This suggests that it is an effective method for use of coordination organics to tether metal ions and prevent their further agglomeration during carbonation.
查看更多>>摘要：We report the top-down modification of intermetallic platinum-cobalt (Pt-Co) nanoparticle catalyst with molybdenum (Mo) promoters that significantly enhance its oxygen reduction activity. With an optimized coverage of the Mo promoters, X-ray absorption spectroscopy reveals the cluster-like Mo species effectively weakened the binding affinity of Pt surfaces towards oxygen. The Mo-promoted intermetallic Pt-Co catalyst thus exhibits high ORR mass activity of 0.89 A/mg_(Pt) compared to 0.22 A/mg_(Pt) and 0.62 A/mg_(Pt) for pure Pt and Pt-Co respectively under rotating disk electrode testing conditions. The high ORR activity further enabled the operation of the fuel cell membrane electrodes under low cathode relative humidities with minimal penalties in ionic transport resistance at low current regions. Density functional theory calculations reveal the beneficial role of molybdenum oxide cluster species in lowering the d-band energy surface Pt atoms, particularly at Pt segregated regions with no Pt-Co phase in proximity to induce the strain or ligand effects.
查看更多>>摘要：The performance of oxygen reduction reaction (ORR) on Fe-N-C single-atom catalysts (SACs) is still less satisfactory due to the rather low atom-utilization of active sites. Here, a novel acetate thermolysis-assisted route is proposed to create hierarchical carbon nanocages of Fe-N-C SACs (FesA~N/Cs-OAc)by selective cleavage of carbon layers, which features abundant edge-sited Fe-N4 moieties in well-defined mesoporous channels. Benefiting from the ultra-high site density and utilization of Fe-N4 moieties, the optimized Fe_(SA)-N/Cs-OAc catalyst demonstrates excellent ORR activities marked by extraordinarily high half-wave potentials (E_(1/2)) of 0.94 V and 0.82 V in alkaline and acidic electrolytes. Zn-air battery using Fe_(SA)-N/Cs-OAc as cathode delivers a power density of 165 mW cm~(-2), and the maximum output power in H2-O2 fuel cell reaches 640 mW cm~(-2). The abundant mesoporosity makes most Fe-N4 sites accessible and simultaneously produces in-plane pore defects that reduced adsorption energy of *OH (-0.72 eV), finally presenting remarkably enhanced ORR performance.
查看更多>>摘要：Reported herein is a study of oxygen vacancies (OVs) provoking the complete mineralization of toluene with Na-doped Co3O4 as a photothermal catalyst. Doping Na~+ into Co3O4 leads to distortion and charge disequilibrium in the Co3O4 lattice, which generates abundant OVs. OVs work as specific centers to convert the absorbed O2 molecules to the active oxygen species O~-. Abundant O~- radicals boost the outermost decomposition of toluene. Comparing the optimal Na-doped Co3O4 (3%Na-Co3O4) with the pristine Co3O4, despite almost the same removal efficiency (100%) on them, the 3%Na-Co3O4 significantly outperforms Co3O4 concerning the CO2 yield in the photothermocatalytic oxidation of toluene under full-spectrum light irradiation (425 mW/cm~2; equilibrium temperature of 218 °C). A mineralization degree of 89.8% is achieved on 3%Na-Co3O4, which is 7-fold higher than that over Co3O4. The OVs also help render the high sustainability of 3%Na-Co3O4 which maintains its outstanding performance even after 10 successive runs.
查看更多>>摘要：The Fe-N-C single-atom catalysts (SACs) have been widely explored for oxygen reduction reaction (ORR) in fuel cells. However, how to improve the ORR activity by tailoring the electronic structure of Fe-N-C catalysts is challenging. Herein, we synthesize a Fe-Mn-N-C dual-atom catalyst (DAC) with new local structure of FeN4-MnN3 moiety, and it exhibits ultralow H2O2 yield and better ORR performance than Fe-N-C and Mn-N-C SACs. Importantly, the Fe-Mn-N-C-based proton-/anion-exchange membrane fuel cells present ultrahigh power densities of 1.048 W cm~(-2) and 1.321 W cm~(-2), respectively. DFT results reveal that the strain yielded by the formation of Mn-Fe bond significantly optimizes the electronic structure of the Fe-Mn-N-C, and the co-adsorption of the Fe-Mn dual-sites for *OOH not only almost completely suppresses the 2e~- ORR, but also breaks the linear correlation between G_(OH*) and G_(OOH*) proposed by Norskov et al., which provides a new route for the design of dual- site catalysts.
查看更多>>摘要：The unique molecular trapdoor mechanism of chabazite zeolites provides an ideal platform for CO2 integrative adsorption and conversion. Herein, a mesoporous In-SSZ-13_((MP))) catalyst was successfully synthesized through desiliconization combined with anchoring uniformly dispersed indium (In) active sites, which achieved the highest formate Faraday efficiency (FE_(HCOO~-)) of 92.0 % and a formate partial current density (jhcoo-) of 133.3 mA cm~(-2) for electrochemical CO2 reduction reaction (CO2RR) at a moderate overpotential of 0.8 V. Experimental results combined with DFT calculations reveal the reaction mechanism of In-SSZ-13_((MP)) electrocatalytic reduction of CO2: as the only channel into the In-SSZ-13_((MP)) crystal, the gatekeeper (cation, In~(3+)) in eight-membered ring (8MR) deviates from its original position induced by CO2 molecule, then CO2 poured into CHA cage and fully reacted with uniformly distributed indium active sites.
NSTL