查看更多>>摘要：The main problem faced by ethanol oxidation reaction(EOR)includes low activity,poor selectivity,and durability.In the study,we found that polysulfide modified on the surface of PtCu intermetallic(IM)/C can simultaneously enrich hydroxyl and ethanol,which could effectively improve the catalytic activity,CO2 selectivity,and durability of catalyst.The mass activity and the specific activity of the product in 1 M KOH electrolyte reached 17.83 A·mgPt-1 and 24.67 mA·cm-2.The CO2 selectivity of polysulfide modified product achieved 93.5％,which was 30 folds higher than Pt/C.In addition,the catalyst showed high catalytic stability.The mechanism study demonstrates that the surface modified polysulfide could significantly boost the enrichment effect of ethanol and hydroxyl species,accelerating C-C bond cleavage and CO oxidation.
查看更多>>摘要：The anodic electrooxidation of ethanol to value-added acetate is an excellent example of replacing the oxygen evolution reaction to promote the cathodic hydrogen evolution reaction and save energy.Herein,we present a colloidal strategy to produce Ni-Fe bimetallic alloy nanoparticles(NPs)as efficient electrocatalysts for the electrooxidation of ethanol in alkaline media.Ni-Fe alloy NPs deliver a current density of 100 mA·cm-2 in a 1.0 M KOH solution containing 1.0 M ethanol merely at 1.5 V vs.reversible hydrogen electrode(RHE),well above the performance of other electrocatalysts in a similar system.Within continuous 10 h testing at this external potential,this electrode is able to produce an average of 0.49 mmol-cm-2·h-1 of acetate with an ethanol-to-acetate Faradaic efficiency of 80％.A series of spectroscopy techniques are used to probe the electrocatalytic process and analyze the electrolyte.Additionally,density functional theory(DFT)calculations demonstrate that the iron in the alloy NPs significantly enhances the electroconductivity and electron transfer,shifts the rate-limiting step,and lowers the energy barrier during the ethanol-to-acetate reaction pathway.
查看更多>>摘要：Emerging as a prominent area of focus in energy conversion and storage technologies,the development of highly active metal-based single-atom catalysts(SACs)holds great significance in searching alternatives to replace precious metals toward the efficient,stable,and low-cost hydrogen evolution reaction(HER),as well as the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR).Combining the tremendous tunability of ligand and coordination environment with rich metal-based electrocatalysts can create breakthrough opportunities for achieving both high stability and activity.Herein,we propose a novel and stable holey graphene-like carbon nitride monolayer g-C16N5(N4@g-C16N3)stoichiometries interestingly behaving as a natural substrate for constructing SACs((TM-N4)@g-C16N3),whose evenly distributed holes map rich and uniform nitrogen coordination positions with electron-rich lone pairs for anchoring transition metal(TM)atoms.Then,we employed density functional theory(DFT)calculations to systematically investigate the electrocatalytic activity of(TM-N4)@g-C16N3 toward HER/OER/ORR,meanwhile considering the synergistic modulation of H-loading and O-coordination((TM-NxO4-x)@g-C16N3-H3,x=0-4).Together a"four-step procedure"screening mechanism with the first-principles high-throughput calculations,we find that(Rh-N4)and(Ir-N2O2-Ⅱ)distributed on g-C16N3-H3 can modulate the adsorption strength of the adsorbates,thus achieving the best HER/OER/ORR performance among 216 candidates,and the lowest overpotential of 0.098/0.3/0.46 V and 0.06/0.48/0.45 V,respectively.Additionally,the d-band center,crystal orbital Hamilton population(COHP),and molecular orbitals are used to reveal the OER/ORR activity source.Particularly,the Rh/Ir-d orbital is dramatically hybridized with the O-p orbital of the oxygenated adsorbates,so that the lone-electrons incipiently locate at the antibonding orbital pair up and populate the downward bonding orbital,allowing oxygenated intermediates to be adsorbed onto(TM-NxO4-x)@g-C16N3-H3 appropriately.
查看更多>>摘要：Biomimetics provides guidance to design and synthesize advanced catalysts for oxygen reduction reaction in microbial fuel cells(MFCs).Herein,jellyfish-inspired Fe clusters on carbon nanotubes connected with CuNC(Fe@CNT@CuNC)were designed and prepared by using zeolitic imidazolate framework(ZIF)-8 precursors to imitate the organic texture and function of jellyfish.The antibacterial effect of Cu+ions depressed the growth of cathode biofilm to ensure rapid mass transport.Fe clusters and CuNC connected by CNTs accelerated the electron transfer from Fe to CuNC.The optimization of oxygen adsorption was caused by electron redistribution between sites of Fe and Cu.Jellyfish-like catalysts achieved a half-wave potential of 0.86 V and onset potential of 0.95 V vs.reversible hydrogen electrode(RHE).MFCs gained the maximum power density of 1600 mW·m-2 after 500 h measurement.This work provides insights into the special design of advanced catalysts based on bio-inspiration and biomimetics.
查看更多>>摘要：The discovery of metal-nitrogen centers as the active sites for electrolysis has aroused significant interest in utilizing single-atom catalysts for nitrogen reduction reaction(NRR).Properly designed nanostructured catalysts that strongly interact with nitrogen molecules(N2)can promote adsorption and activation,thereby resulting in efficient catalysts with high stability,activity,and selectivity.In this study,using density functional theory calculations,we selected monolayer black phosphorus(BP)as the substrate and screened a series of single-atom transition metals confined in tri-coordinated and tetra-coordinated active centers(without and with N dopants)to electro-catalyze NRR.As a result,we have identified two promising candidates(Hf1-N1P2-1 and Tc1-N4),which exhibit not only low overpotentials of 0.56 and 0.49 V but also high thermodynamic and electrochemical stability,as well as good selectivity towards NRR over the competing hydrogen evolution reaction.We also demonstrate the ability of Hf1-N1P2-1 and Tc1-N4 to activate and hydrogenate N2 by donating electrons and regulating charge transfer.This study not only predicts new BP-based promising catalysts but also provides guidance for the rational design of high-performance NRR electrocatalysts under ambient conditions.
查看更多>>摘要：Graphitic carbon nitride(g-C3N4)nanosheets have attracted widespread interest in the construction of advanced separation membranes.However,dense stacking and a single functionality have limited the membrane development.Here,an advanced two-/three-dimensional(2D/3D)g-C3N4/TiO2@MnO2 membrane is constructed by intercalating 3D TiO2@MnO2 nanostructures into g-C3N4 nanosheets.The 3D flower-like nanostructures broaden the transport channels of the composite membrane.The membrane can effectively separate five oil-in-water(O/W)emulsions,with a maximum flux of 3265.67±15.01 L·m-2·h-1·bar-1 and a maximum efficiency of 99.69％±0.45％for toluene-in-water emulsion(T/W).Meanwhile,the TiO2@MnO2 acts as an excellent electron acceptor and provides positive spatial separation of electrons-holes(e--h+).The formation of 2D/3D heterojunctions allows the material with wider light absorption and smaller bandgap(2.10 eV).These photoelectric properties give the membrane good degradation of three different pollutants,with about 100％degradation for methylene blue(MB)and malachite green(MG).The photocatalytic antibacterial efficiency of the membrane is also about 100％.After cyclic experiment,the membrane maintains its original separation and photocatalytic capabilities.The remarkable multifunctional and self-cleaning properties of the g-C3N4 based membrane represent its potential value for complex wastewater treatment.
查看更多>>摘要：CO2 electroreduction to formic acid/formate would contribute to alleviating the energy and climate crisis.This work reports a Bi-based catalyst derived from the in-situ electroreduction of Bi2O2CO3 modified with iodine and pyrenyl-graphdiyne(PGDY)on the surface for efficient electroreduction of CO2 in acidic electrolyte,with a high partial current density of 98.71 mA·cm-2 and high Faradaic efficiency(FE)＞90％over the potential range from-1.2 to-1.5 V vs.reversible hydrogen electrode(RHE),as well as the long-term operational stability over 240 h without degradation in H-type cell.Experimental results and density function theory calculations show that the synergistic effect of surface iodine and PGDY is responsible for this active and extremely stable process of CO2 electroreduction via lowering the energy barriers for formation of*OCHO intermediate,suppressing the competitive HER by enhancing the concentration of both K+and CO2 at reaction interface,as well as preventing the dissolution and re-deposition of active Bi atoms on surface during catalytic reaction.This work provides new insight into designing highly active and stable electrocatalysts for CO2 reduction.
查看更多>>摘要：The sluggish kinetics of oxygen evolution reaction(OER)is the key tailback for hydrogen production from the water electrolysis.Masking OER with thermodynamically auspicious methanol oxidation reaction(MOR)can significantly boost the H2 and value-added products production.However,it is currently challenging to achieve a synergistic manipulation of product selectivity and performance for MOR electrocatalyst.Herein,we report NiSnPH@OOH/CC(CC=carbon cloth)perovskite hydroxide nanosphere as an efficient MOR electrocatalyst with high activity,stability,and selectivity towards methanol oxidation to formate.A surface amorphous layer of defect rich NiOOH was generated in operando by selective Sn leaching with stable perovskite hydroxide bulk structure,which mitigates the oxidative power and optimizes the local coordination environment of the active NiOOH sites.In situ Raman combined with electrochemical studies further confirm the key active species,NiOOH,generated in operando enhance the MOR and blocking the over oxidation of methanol to CO2.As a result,NiSnPH@OOH/CC effectively masks the OER and attains＞99％selectivity with 100％Faradic efficiency for methanol-to-formate.The results of this study show the advances of NiSnPH@OOH/CC as an efficient electrocatalyst for MOR and also suggest its potential applications for various small organic molecules oxidation.
查看更多>>摘要：The solar-driven reduction of CO2 into valuable products is a promising method to alleviate global environmental problems and energy crises.However,the low surface charge density limits the photocatalytic conversion performance of CO2.Herein,a polymeric carbon nitride(PCN)photocatalyst with Zn single atoms(Zn1/CN)was designed and synthesized for CO2 photoreduction.The results of the CO2 photoreduction studies show that the CO and CH4 yields of Zn1/CN increased fivefold,reaching 76.9 and 22.9 pmol/(g·h),respectively,in contrast to the unmodified PCN.Ar+plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn-N4 configuration.Photoelectrochemical characterizations indicate that the interlayer Zn-N4 configuration can amplify light absorption and establish an interlayer charge transfer channel.Light-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn-N4 configuration,which increases its surface charge density.Further,in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates(*COOH)conversion,thus achieving efficient CO2 conversion.This work elucidates the role of internal single atoms in catalytic surface reactions,which provides important implications for the design of single-atom catalysts.
查看更多>>摘要：Assembly of two-dimensional(2D)metal-organic layers(MOLs)based on the hard and soft acid-base theorem represents an exquisite strategy for the construction of photocatalytic platforms in virtue of the highly exposed active sites,much improved mass transport,and greatly elevated stability.Herein,nanocages composed of MOLs are produced for the first time through a cosolvent approach utilizing zirconium-based UiO-66-(OH)2 as the structural precursor.To endow the catalytic activity for CO2 conversion,single atomic Co2+sites are appended to the Zr-oxo nodes of the MOL cages,demonstrating a remarkable CO yield of 7.74 mmol·g-1·h-1 and operational stability of 97.1％product retention after five repeated cycles.Such an outstanding photocatalytic performance is mainly attributed to the unique nanocage morphology comprising enormous 2D nanosheets for augmented Co2+exposure and the abundant surface hydroxyl groups for local CO2 enrichment.This work underlines the tailoring of both metal-organic framework(MOF)morphology and functionality to boost the turnover rate of photocatalytic CO2 reduction reaction(CO2RR).
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