Highly Efficient Electrochemical Reduction Of Carbon Monoxide To Multi-Carbon Products

The increasing global demand for energy,coupled with growing environmental concerns,has made the development of sustainable energy conversion and carbon reduction technologies a critical priority.Among these,the electrochemical reduction of carbon monoxide(CO)stands out as a promising approach to convert greenhouse gases into valuable chemicals.However,challenges such as improving product selectivity,reducing energy consumption,and creating efficient and stable catalysts persist.This thesis aims to address these challenges by focusing on the efficient and selective electrochemical reduction of CO through the design and synthesis of innovative nanomaterials,the optimization of electrolyzer structures,and the integration of biomass oxidation with CO reduction reactions.The key research objectives are as follows:1.The research successfully synthesized Cu-Ni bimetallic alloy nanomaterials using a two-step reduction method and Cu-Sn nanomaterials through an oleylamineoleic acid system.X-ray diffraction(XRD)and transmission electron microscopy(TEM)analyses confirmed the crystal structures and morphologies of these alloys.The electrocatalytic performance tests for CO reduction revealed that the catalytic activity of Cu-Ni nanomaterials was highly dependent on the Ni content,while Cu-Sn nanomaterials predominantly produced acetate,showing a distinct reaction trend compared to pure Cu nanomaterials.2.The exploration of the synthesis,structural characterization,and electrocatalytic CO reduction performance of PdCu nanomaterials with diverse morphologies has been documented.Utilizing a liquid-phase synthesis method,PdCu nanomaterials were produced,encompassing dendritic,multipod,nanorods,nanowires,and spherical nanoparticles.Phase analysis confirmed the formation of face-centered cubic PdCu alloys across all materials.Morphological analysis revealed the size distribution and monodispersity of the nanomaterials,with nanowires and nanorods exhibiting unique one-dimensional structures.The electrocatalytic performance tests indicated that these PdCu nanomaterials showed varied product distributions and H2 faradaic efficiencies at a current density of 200 mA cm-2.Notably,multipod nanoparticles had the highest ethylene generation rate,while PdCu nanorods were more efficient for methane production.3.A comprehensive study was conducted on the synthesis,structural characterization,electrocatalytic performance,CO adsorption strength,and membrane electrode testing of multicomponent M-PdCu nanomaterials.The incorporation of a third metal element,including but not limited to Mo,W,Ni,Fe,Pb,Mn,and Co,has led to the synthesis of a series of M-PdCu alloy nanomaterials.These materials displayed exceptional electrocatalytic activity for CO reduction in a 1 M KOH solution,with the Ni-PdCu alloy achieving an acetate faradaic efficiency of about 36.5%.In a 5 M KOH solution,the acetate faradaic efficiency reached 59.4%,indicating superior performance under high alkaline conditions.CO-temperature-programmed desorption(CO-TPD)studies confirmed that the addition of a third metal element significantly enhanced the CO adsorption strength of PdCu alloys.Membrane electrode test results showed that the Ni-PdCu catalyst maintained high acetate selectivity and stability over more than 100 hours of testing.4.A novel electrolyzer design has been introduced,integrating biomass oxidation with CO reduction reactions.Four electrooxidation catalysts—NiOOH,CoOOH,(Ni,Co)OOH,and NiFe-LDH—were synthesized and their performance was assessed in the electrooxidation of N-acetylglucosamine(NAG)and chitin.The(Ni,Co)OOH catalyst exhibited the highest activity in the NAG oxidation reaction.The custom-built electrolyzer employs(Ni,Co)OOH as the electrooxidation catalyst and Cu/C as the CO reduction catalyst to explore the coupling efficiency between biomass oxidation and CO reduction reactions.The experimental results showed that,compared to traditional oxygen evolution reaction coupling,the biomass oxidation coupling system significantly increased the acetate generation rate and faradaic efficiency while reducing energy consumption.At a test voltage of 2.2 V,the electrolyzer coupled with ballmilled chitin oxidation achieved an acetate production rate of 364.5 μmol h-1 cm-2,which is 16 times that of traditional electrolyzers,with an apparent faradaic efficiency increase of 32.1%.Moreover,the energy consumption per mole of acetate generated in the CORR//COR and CORR//NAGOR systems was 0.77 Wh,a reduction of approximately 67%compared to the CORR//OER system.