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.

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.

Leather waste as precursor to prepare bifunctional catalyst for alkaline and neutral zinc-air batteries

Carbon materials derived from biomass waste are considered as potential electrocatalysts for applications in zinc-air batteries(ZABs)due to their low cost and good catalytic activity.Here,we reported the preparation of gel-based catalysts through utilizing hydrolyzed waste leather powder cross-linked with metallic salt solutions.After calcination,iron-nickel alloy anchored in nitrogen-doped porous carbon catalysts(Fe Ni@NDC)was achieved.Compared with commercial Pt/C catalyst,Fe Ni@NDC-800 exhibited lower E_(1/2)(0.77 V)and better durability.More importantly,the resulting Fe Ni@NDC-800-based alkaline ZABs achieved power density of 93.01 m W/cm^(2) and open circuit voltage of 1.45 V,which the Fe Ni@NDC-800-based neutral ZAB displayed a charge/discharge cycle stability of 275 h.This work opens up the possibility of rational design and preparation of low-cost and high-performance electrocatalysts from recyclable leather waste.

Unraveling and tuning the linear correlation between CH_(4) and C_(2) production rates in CO_(2) electroreduction

Although many catalysts have been reported for the CO_(2)electroreduction to C_(1)or C_(2)chemicals,the insufficient understanding of fundamental correlations among different products still hinders the development of universal catalyst design strategies.Herein,we first discover that the surface*CO coverage is stable over a wide potential range and reveal a linear correlation between the partial current densities of CH_(4)and C_(2)products in this potential range,also supported by the theoretical kinetic analysis.Based on the mechanism that*CHO is the common intermediate in the formation of both CH_(4)(*CHO→CH4)and C_(1)(*CHO+*CO→C_(2)),we then unravel that this linear correlation is universal and the slope can be varied by tuning the surface*H or*CO coverage to promote the selectivity of CH_(4)or C_(2)products,respectively.As proofs-of-concept,using carbon-coated Cu particles,the surface*H coverage can be increased to enhance CH_(4)production,presenting a high CO_(2)-to-CH_(4)Faradaic efficiency(FE_(CH_(4))~52%)and an outstanding CH_(4)partial current density of-337 m A cm;.On the other hand,using an Agdoped Cu catalyst,the CO_(2)RR selectivity is switched to the C_(2)pathway,with a substantially promoted FE;of 79%and a high partial current density of-421 m A cm;.Our discovery of tuning intermediate coverages suggests a powerful catalyst design strategy for different CO_(2)electroreduction pathways.