Photo-and Electrocatalytic CO_(2)Reduction Based on Stable Lead-Free Perovskite Cs2PdBr6

All-inorganic lead-free palladium(Pd)halogen perovskites with prominent optoelectronic properties provide admirable potential for selective photo-and electroreduction of CO_(2).But it remains unachieved for effectively converting the CO_(2)to CO with high selectivity on Pd-based perovskites driven by solar light or electricity.Herein,high-quality Cs_(2)PdBr_(6)microcrystals and nanocrystals were synthesized through a facile antisolvent method.Among all the reported pure-phase perovskites,the Cs_(2)PdBr_(6)nanocrystals synthesized at 50℃performed the highest effectiveness on CO_(2)to CO conversion generating 73.8μmol g^(-1)of CO yield with 100%selectivity under visible light illumination(λ>420 nm)for 3 h.Meanwhile,for the first time,we report a new application of lead-free perovskites,in which they are applied to electrocatalysis of CO_(2)reduction reaction.Noticeably,they showed significant electrocatalytic activity(Faradaic yield:78%for CO)and operation stability(10 h).And the surface reaction intermediates were dynamically monitored and precisely unraveled according to the in situ diffuse reflectance infrared Fourier transform spectra investigation.In combination with the density functional theory calculation,the reaction mechanism and pathways were revealed.This work not only provides significant strategies to enhance the photocatalytic performance of perovskites,but also shows excellent potential for their application in electrocatalysis.

Progresses on carbon dioxide electroreduction into methane

The conversion of CO_(2) into value‐added chemicals and fuels via electrochemical methods paves a promising avenue to mitigate both energy and environmental crisis.Among all the carbonaceous products derived from CO_(2) electroreduction,CH_(4) is one of the most important carriers for chemical bond energy storage due to the highest value of mass heat.Herein,starting from the proposed reaction mechanisms reported previously,we summarized the recent progresses on CO_(2) electroreduction into CH_(4) from the perspective of catalyst design strategies including construction of subnanometer catalytic sites,modulation of interfaces,in‐situ structural evolution,and engineering of tandem catalysts.On the basis of both the previously theoretical predictions and experimental results,we aimed to gain insights into the reaction mechanism for the formation of CH_(4),which,in turn,would provide guidelines for the design of highly efficient catalysts.

Applications of in-situ spectroscopic techniques towards CO_(2)electroreduction

In-situ experimental techniques have been widely applied to uncover the dynamic evolutions of both the structure of catalysts and the interfacial property of catalysis,thus serving as the most important means to gain molecular-level insights into the reaction mechanisms.In this mini review,we summarized recent progress in the applications of the interface-sensitive in-situ Raman and in-situ infrared(IR)spectroscopy towards CO_(2)electroreduction.Specifically,we concentrated on two aspects to clarify the role of both in-situ Raman and in-situ IR in revealing reaction mechanisms of CO_(2)electroreduction.The first one was the in-situ spectroscopy for detecting the active structures.The other one was the in-situ spectroscopy for capturing the reaction intermediates.As powerful guidance for the rational design of catalysts,the reaction mechanism was discussed in the specific examples.Finally,we try to predict the trends for the future development of in-situ spectroscopic techniques towards heterogeneous catalysis.

Thiol Ligand-Modified Au for Highly Efficient Electroreduction of Nitrate to Ammonia

Electroreduction of nitrate(NO_(3)-)to ammonia(NH_(3))is an environmentally friendly route for NH_(3)production,serving as an appealing alternative to the Haber-Bosch process.Recently,various noble metal-based electrocatalysts have been reported for electroreduction of NO_(3)-.However,the application of pure metal electrocatalysts is still limited by unsatisfactory performance,owing to the weak adsorption of nitrogen-containing intermediates on the surface of pure metal electrocatalysts.In this work,we report thiol ligand-modified Au nanoparticles as the effective electrocatalysts toward electroreduction of NO_(3)-.Specifically,three mercaptobenzoic acid(MBA)isomers,thiosalicylic acid(ortho-MBA),3-mercaptobenzoic acid(meta-MBA),and 4-mercaptobenzoic acid(para-MBA),were employed to modify the surface of the Au nanocatalyst.During the NO_(3)-electroreduction,para-MBA modified Au(denoted as para-Au/C)displayed the highest catalytic activity among these Au-based catalysts.At-1.0 V versus reversible hydrogen electrode(vs RHE),para-Au/C exhibited a partial current density for NH_(3)of 472.2 mA cm^(-2),which was 1.7 times that of the pristine Au catalyst.Meanwhile,the Faradaic efficiency(FE)for NH_(3)reached 98.7%at-1.0 V vs RHE for para-Au/C.The modification of para-MBA significantly improved the intrinsic activity of the Au/C catalyst,thus accelerating the kinetics of NO_(3)-reduction and giving rise to a high NH_(3)yield rate of para-Au/C.

Electrodeposited highly-oriented bismuth microparticles for efficient CO_(2)electroreduction into formate

Bi is one of the most fascinating catalysts for the formation of HCOO-towards CO_(2)electroreduction.Herein,we developed electrodeposited angular-shaped Bi microparticles(Bi MP)with exposed surfaces of{003}and{101}planes as efficient catalyst for the electroreduction of CO_(2)into HCOO-.During CO_(2)electroreduction,Bi MP achieved a Faraday efficiency(FE)for HCOO-of higher than 95%over a wide range of applied potential from-0.6 to-1.1 V versus reversible hydrogen electrode(vs.RHE),whereas the FE for HCOO-of Bi nanoflakes(Bi NF)with exposed surfaces of{104}and{110}planes was around 70%.At-1.1 V vs.RHE,the partial current density for HCOO-of Bi MP was-271.7 mA·cm-2,1.56 times as high as that of Bi NF.According to kinetic analysis and mechanistic study,highly-oriented surface of Bi MP not only facilitated Faradaic process and accelerated reaction kinetics via enhancing the CO_(2)activation,but also restrained competing hydrogen evolution reaction,thus boosting catalytic performance of the electroreduction of CO_(2)into HCOO-.

Enhance the activity of multi-carbon products for Cu via P doping towards CO_(2) reduction

Electronic structure engineering is a powerful method to tailor the behavior of adsorbed intermediates on the surface of catalysts,thus regulating catalytic activity towards CO_(2)electroreduction.Herein,we prepared a series of P-doped Cu catalysts for CO_(2)electroreduction into multi-carbon(C_(2+))products by regulating the surface electronic structure of Cu.The introduction of P could stabilize the surface Cu^(δ+)species,enhancing the activity for C_(2+)products via adjusting the adsorbed strength of the CO intermediates(~*CO).When the molar ratio of P to Cu was 8.3%,the catalyst exhibited a Faradaic efficiency of 64%for C_(2+)products,which was 1.9 times as high as that(33%)for Cu catalysts at the applied current density of 210 m A cm^(-2).Notably,at the applied current density of 300 mA cm^(-2),the P-doped Cu catalyst with the molar ratio of P to Cu of 8.3%exhibited the highest partial current density for C_(2+)products of 176 mA cm^(-2),whereas the partial current density for C_(2+)products over the Cu catalyst was only 84 mA cm^(-2).Mechanistic studies revealed that modulating the molar ratios of P to Cu regulated the adsorbed strength of~*CO.A moderate adsorbed strength of *CO induced by appropriate P doping was responsible for the facilitated C–C coupling process.