Electroreduction of air‐level CO_(2) with high conversion efficiency

The electrochemical conversion of carbon dioxide(CO_(2))has been attracting increasingly research interest in the past decade,with the ultimate goal of utilizing electricity from renewable energy to realize carbon neutrality,as well as economic and energy benefits.Nonetheless,the capture and concentrating of CO_(2) cost a substantial portion of energy,while almost all the reported researches showed CO_(2) electroreduction under high concentrations of(typically pure)CO_(2) reactants,and only very few recent studies have investigated the capability of applying low CO_(2) concentrations(such as~10%in flue gases).In this work,we first demonstrated the electroreduction of 0.03%CO_(2)(in helium)in a homemade gas‐phase electrochemical electrolyzer,using a low‐cost copper(Cu)or nanoscale copper(nano‐Cu)catalyst.Mixed with steam,the gas‐phase CO_(2) was directly delivered onto the gas‐solid interface with the Cu catalyst and reduced to CO,without the need/constraint of being adsorbed by aqueous solution or alkaline electrolytes.By tuning the catalyst and experi‐mental parameters,the conversion efficiency of CO_(2) reached as high as~95%.Furthermore,we demonstrated the direct electroreduction of 0.04%CO_(2) from real air sample with an optimized conversion efficiency of~79%,suggesting a promising perspective of the electroreduction ap‐proach toward direct CO_(2) conversion.

Copper‐doped nickel oxyhydroxide for efficient electrocatalytic ethanol oxidation

Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.

Efficient CO_(2) fixation with acetophenone on Ag-CeO_(2) electrocatalyst by a double activation strategy

The electrocarboxylation reaction is an attractive means to convert CO_(2) into valuable chemicals under ambient conditions,while it still suffers from low efficiency due to the high stability of CO_(2).In this work,we report a double activation strategy for simultaneously activating CO_(2) and acetophenone by silver-doped CeO_(2)(Ag-CeO_(2)) nanowires,featuring as an effective electrocatalyst for electrocarboxylation of acetophenone with CO_(2).Compared to the Ag foil,Ag nanoparticles and CeO_(2) nanowires,the Ag-CeO_(2)nanowire catalyst allowed to reduce the onset potential difference between CO_(2) and acetophenone activation,thus enabling efficient electrocarboxylation to form 2-phenyllactic acid.The Faradaic efficiency for producing 2-phenyllactic acid reached 91%at−1.8 V versus Ag/AgI.This double activation strategy of activating both CO_(2)and organic substrate molecules can benefit the catalyst design to improve activities and selectivities in upgrading CO_(2)fixation for higher-value electrocarboxylation.

Enhanced N-doping in mesoporous carbon for efficient electrocatalytic CO2 conversion

The capability of electrocatalytic reducti on of carbon dioxide(CO2)using nitrogen(N)-doped carb on strongly depe nds on the N-dopi ng level and their types.In this work,we developed a strategy to generate mesoporous N-doped carb on frameworks with tun able configurati ons and contents of N dopants,by using a secondary doping process via the treatment of N,N-dimethylformamide(DMF)solvent.The obtained mesoporous N-doped carbon(denoted as MNC-D)served as an efficient electrocatalyst for electroreduction of CO2 to CO.A high Faradaic efficiency of^92%and a partial current density for CO of-6.8 mA·cm^-2 were achieved at a potential of-0.58 V vs.RHE.Electrochemical analyses further revealed that the active sites within the N-doped carb on catalysts were the pyridinic N and defects gen erated by the DMF treatme nt,which enhan ced the activati on and adsorpti on CO2 molecules.Our study suggests a new approach to develop efficie nt carb on-based catalysts for potential scalable CO2 reduction reaction(CO2RR)to fuels and chemicals.

Synthesis and optical characterization of Eu^(2+),Tb^(3+)-codoped Sr_3Y(PO_4)_3 green phosphors

A series of Eu^2＋,Tb^3＋-codoped Sr3 Y（PO4）3（SYP） green phosphors were synthesized by hightemperature solid-state reaction. Several techniques, such as X-ray diffraction, UV-vis spectrum,and photoluminescence spectrum, were used to investigate the obtained phosphors. The present study investigates in detail photoluminescence excitation and emission properties, energy transfer between the two dopants, and effects of doping ions on optical band gap. SYP：0.05 Eu2＋ phosphor shows an intense and broad excitation band ranging from 220 to 400 nm and exhibits a bright green emission band with CIE chromaticity coordinates（0.189, 0.359） under 350 nm excitation. Green emission of SYP：0.03 Tb3＋ is intensified by codoping with Eu^2＋, and energy transfer mechanism between them is demonstrated to be a dipole-dipole interaction. Upon 350 nm excitation, SYP：Eu^2＋,Tb^3＋ phosphors exhibits two dominating bands peaking at 466 and 545 nm, which are assigned to 4 f^65 d^1→4 f^7 transition of Eu^2＋ ions and ~5 D4→~7 F5 transition of Tb^3＋ ions, respectively. Optimal doping concentrations of Eu^2＋ and Tb^3＋ in the SYP host are 5 mol% and 15 mol%, respectively. Results indicate that SYP：Eu^2＋,Tb^3＋ phosphors are potentially used as green-emitting phosphors for white light-emitting diodes.