| Carbon monoxide is one of the key resources in C1 catalysis which involves in water-gas shift(WGS)reaction for hydrogen(H2)production and conversion of syngas to high value-added products.The thermocatalytic CO conversion process usually operates under high temperature and pressure,and requires additional separation of products from undesired chemicals.Thus,it is promising and challenging to convert CO to high value-added products by environmentally friendly strategy with low-energy consumption.The reaction pathway can be controlled by voltage optimization under ambient temperature and pressure which can improve selectivity and avoid harsh conditions in thermocatalytic process.In this thesis,through designing new electrocatalytic process,rational optimizing catalysts and electrodes,and improving CO diffusion,etc.,room-temperature electrochemical water-gas shift(RT-EWGS)reaction and highly selective CO electroreduction to ethylene process are achieved.The main results are summarized as following:(1)Room-temperature electrochemical water-gas shift process for high purity H2(>99.99%)production is firstly reported.Through designing structure of electrode and modifying Pt@CNTs catalysts with hydrophobic polytetrafluoroethylene(PTFE)to facilitate CO diffusion,RT-EWGS process with a H2 faradaic efficiency(FE)of nearly 100%is achieved at ambient pressure and temperature.Combining density functional theory(DFT)calculations,we optimize the electron structure of Pt and design the PtCu catalysts.The anodic onset potential is lowered to almost 0 V and the optimized Pt2.7Cu@CNTs catalyst achieves a current density of 70.0 mA cm-2 at 0.6 V.Besides,RT-EWGS process can remain stable for even more than 475 hours.This study provides a new and promising route of directly producing high purity H2.(2)Room-temperature electrochemical water-gas shift reaction in acid and neutral electrolytes is explored through designing the gas diffusion electrolytic cell and membrane electrode assemblies(MEA).The improvement of electrolytic cell avoids the lack of CO in solutions and the consumption of KOH electrolytes.Besides,the content of precious metal in catalysts are decreased compared with Pt@CNTs and Pt2.7Cu@CNTs catalysts.Moreover,CO content of H2 generated from RT-EWGS process in acid solution is lowered to 12.5 ppm.Besides,onset potential of RT-EWGS reaction over optimized PtRu-CNTs catalysts is 0.24 V lower than that over Pt-CNTs.A H2 production current density of 46.7 mA cm-2 is achieved at 1.0 V in 0.5 M H2SO4 solution.(3)A direct electrocatalytic process for highly selective ethylene production from CO reduction with water at room-temperature and ambient pressure is achieved.Through rational optimization of PTFE content to construct the hydrophobic microenvironment in gas/liquid/solid three phase interfaces,the activity of CO electroreduction is increased greatly.Electrocatalytic CO reduction to ethylene process can achieve an unprecedentedly high ethylene FE of 52.7%after optimizing Cu-based catalysts and OH-concentration.Moreover,the selectivity of ethylene production based on CO conversion is approximately 70%which breaks through the 30%selectivity limitation from CO to C2 hydrocarbons in Fischer-Tropsch synthesis process.Besides,DTF calculations suggest that Cu(100)is the most preferred plane for C2H4 formation via considering all possible products. |
