Low-temperature Catalytic Reduction of Nitrogen Monoxide with Carbon Monoxide on Copper Iron and Copper Cobalt Composite Oxides

Copper iron composite oxides （CuO/Fe2O3） and copper cobalt composite oxides （CuO/Co3O4） for the catalytic reduction of NO with CO at low temperature were prepared by co-precipitation. The catalytic activity and thermal stability of the catalysts were evaluated by a microreactor-GC system. The 100% conversion temperatures of NO are 80 ℃ for CuO/Fe2O3 and 90 ℃ for CuO/Co3O4. The catalysts possess high catalytic activity and favorable thermal stability for NO reduction with CO in a wide temperature range and long time range. A systematic study of the molar ratios of the reactants, the volume of NaOH, aging time, and calcination temperature/time was carried out to investigate the influence preparation conditions on the catalytic activity of the catalysts.

Advances in bio-inspired electrocatalysts for clean energy future

Electrocatalysis can enable efficient energy storage and conversion and thus is an effective way to achieve carbon neutrality.The unique structure and function of organisms can offer many ideas for the design of electrocatalysts,which has become one of the most promising research directions.Recently,the understanding of the mechanism of bio-inspired electrocatalysis has become clearer,which has promoted the design of bio-inspired catalysts and catalytic systems.Various bio-inspired catalysts(enzyme-like catalysts,layered porous catalysts,superhydrophobic/superhydrophilic surfaces,and so on)have been developed to enable efficient electrocatalytic reactions.Herein,we discuss the key advances in the field of bio-inspired electrocatalysts progressed in recent years.First,the role of bio-inspiration in increasing the intrinsic activity and number of active sites of catalysts is introduced.Then,the structure and mechanism of layered porous catalytic systems that mimic biological transport systems are comprehensively discussed.Subsequently,the design of three-phase interfaces from micro-nanoscale to atomic scale is highlighted,including the wettability of the electrode surface and the transport system near the electrode.We conclude the review by identifying challenges in bio-inspired electrocatalysts and providing insights into future prospects for the exciting research field.

Investigation and Mitigation of Carbon Deposition over Copper Catalyst during Electrochemical CO_(2)Reduction

Copper(Cu)is considered to be the most effective catalyst for electrochemical conversion of carbon dioxide(CO_(2))into value-added hydrocarbons,but its stability still faces considerable challenge.Here,we report the poisoning effect of carbon deposition during CO_(2)reduction on the active sites of Cu electrodea critical deactivation factor that is often overlooked.We find that,*C,an intermediate toward methane formation,could desorb on the electrode surface to form carbon species.We reveal a strong correlation between the formation of methane and the carbon deposition,and the reaction conditions favoring methane production result in more carbon deposition.The deposited carbon blocks the active sites and consequently causes rapid deterioration of the catalytic performance.We further demonstrate that the carbon deposition can be mitigated by increasing the roughness of the electrode and increasing the pH of the electrolyte.This work offers a new guidance for designing more stable catalysts for CO_(2)reduction.

Towards reliable assessment of hydrogen oxidation electrocatalysts for anion-exchange membrane fuel cells

Recent advancement of proton exchange membrane fuel cells has led to commercial sales of fuel-cell cars but market barrier exists because this technology heavily relies on platinum catalyst.Given the permission of adopting platinum-group-metal-free catalysts,anion-exchange membrane fuel cell has received notable attention.However,the sluggish kinetics of anodic hydrogen oxidation reaction(HOR)largely limit the cell efficiency.Although many high-performance HOR catalysts have been reported,there are analytical uncertainties in the literature concerning the assessment of the catalyst activity.Here we determine the origin of false HOR currents in the recorded polarization curves and propose a rigorous approach to eliminate them.We unveil experimentally the uncertainties of obtaining exchange current densities(j0)using Tafel plot from Bulter–Volmer equation and recommend employing the micro-polarization region method.For bulky catalysts that cannot establish a well-defined diffusion layer,we suggest applying external stirring bar to offer certain level of enforced convection and using j0 to compare the activity.

Modular divergent creation of dual-cocatalysts integrated semiconducting sulfide nanotriads for enhanced photocatalytic hydrogen evolution

Heteronanostructures(HNs)with precise components and interfaces are important for many applications,such as designing efficient and robust solar-to-fuel catalysts via integrating specific semiconductors with favorable band alignments.However,rationally endowing such features with rigorous framework control remains a synthetic bottleneck.Herein,we report a modular divergent creation of dual-cocatalysts integrated semiconducting sulfide nanotriads(NTds),comprising both isolated Pd_(x)S oxidation(ox)and MoS_(2) reduction(red)domains within each single CdS counterpart,which exhibit superior photocatalytic activity and stability for hydrogen evolution reaction(HER).The stepwise constructed Pd_(x)S_((ox))−CdS−MoS_(2(red)) NTds possess dualinterfaces facilitating continuous charge separation and segregated active sites accelerating redox reactions,respectively,achieving the HER rate up to 9 mmol·h^(−1)·g^(−1),which is about 60 times higher than that of bare CdS,and show no evidence of deactivation after long-term cycling.This design principle and transformation protocol provide predictable retrosynthetic pathways to HNs with increased degree of complexity and more elaborate functionalities that are otherwise inaccessible.

CO_(2)-assisted formation of grain boundaries for efficient CO–CO coupling on a derived Cu catalyst

The electrochemical CO_(2)reduction reaction(CO_(2)RR)on Cu catalyst holds great promise for converting CO_(2)into valuable multicarbon(C_(2+))compounds,but still suffers poor selectivity due to the sluggish kinetics of forming carbon–carbon(C–C)bonds.Here we reported a perovskite oxide-derived Cu catalyst with abundant grain boundaries for efficient C–C coupling.These grain boundaries are readily created from the structural reconstruction induced by CO_(2)-assisted La leaching.Using this defective catalyst,we achieved a maximum C_(2+)Faradaic efficiency of 80.3%with partial current density over 400 mA cm−2 in neutral electrolyte in a flow-cell electrolyzer.By combining the structural and spectroscopic investigations,we uncovered that the in-situ generated defective sites trapped by grain boundaries enable favorable CO adsorption and thus promote C–C coupling kinetics for C_(2+)products formation.This work showcases the great potential of perovskite materials for efficient production of valuable multicarbon compounds via CO_(2)RR electrochemistry.

Unconventional dual-vacancies in nickel diselenide-graphene nanocomposite for high-efficiency oxygen evolution catalysis

Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting,it is still imperative to enhance their activity for real device applications.Herein,we decorated Ni0.85Se hollow nanospheres onto reduced graphene oxide(RGO)through a hydrothermal route,then annealed this composite at different temperatures(400℃,NiSe2-400 and 450℃,NiSe2-450)under argon atmosphere,yielding a kind of NiSe2/RGO composite catalysts.Positron annihilation spectra revealed two types of vacancies formed in this composite catalyst.We found that the NiSe2-400 catalyst with dual Ni-Se vacancies is able to catalyze the oxygen evolution reaction(OER)efficiently,needing a mere 241 mV overpotential at 10 mA·cm−2.In addition,this catalyst exhibits outstanding stability.Computational studies show favorable energy barrier on NiSe2-400,enabling moderate OH−adsorption and O2 desorption,which leads to the enhanced energetics for OER.

Synthesis of PdS_(x)- Mediated Polydymite Heteronanorods and Their Long-Range Activation for Enhanced Water Electroreduction

Material interfaces permit electron transfer that modulates the electronic structure and surface properties of catalysts,leading to radically enhanced rates for many important reactions.Unlike conventional thoughts,the nanoscale interfacial interactions have been recently envisioned to be able to afect the reactivity of catalysts far from the interface.However,demonstration of such unlocalized alterations in existing interfacial materials is rare,impeding the development of new catalysts.We report the observation of unprecedented long-range activation of polydymite Ni_(3)S_(4) nanorods through the interfacial interaction created by PdS_(x) nanodots(dot-on-rod structure)for high-performance water catalytic electroreduction.Experimental results show that this local interaction can activate Ni3S4 rods with length even up to 25 nanometers due to the tailored surface electronic structure.We anticipate that the long-range efect described here may be also applicable to other interfacial material systems,which will aid the development of newly advanced catalysts for modern energy devices.

Phase-Controlled 1T Transition-Metal Dichalcogenide-Based Multidimensional Hybrid Nanostructures

Metallic-phase transition-metal dichalcogenides(TMDCs)exhibit unusual physicochemical properties compared with their semiconducting counterparts.However,they are thermodynamically unstable to access and it is even more challenging to construct their metastable-phase heterostructures.Herein,we demonstrate a general solution protocol for phase-controlled synthesis of distorted octahedral 1T WS2-based(1T structure denotes an octahedral coordination for W atom)multidimensional hybrid nanostructures from two-dimensional(2D),one-dimensional(1D),and zero-dimensional(0D)templates.This is realized by tuning the reactivity of tungsten precursor and the interaction between crystal surface and ligands.As a conceptual study on crystal phase-and dimensionality-dependent applications,we find that the three-dimensional(3D)hierarchical architectures achieved,comprising 1T WS2 and 2D Ni3S4,are very active and stable for catalyzing hydrogen evolution.Our results open up a new way to rationally design phase-controlled nanostructures with increased complexity and more elaborate functionalities.