Preparation Of Cathode Material Using Zeolite As Carrier For Electrocatalytic Hydrogen Evolution Performance In Microbial Electrolysis Cell

To realize the sustainable development of China’s energy industry,it is necessary to speed up the transformation of energy development mode and deepen the reform of the energy system in an all-round way so as to establish a clean,low-carbon,safe and efficient modern energy system.Therefore,clean energy has grown up to be an important part of China’s energy revolution.Microbial electrolysis cell（MEC）is a completely new and promising technology that can utilize the organic matter,including wastewater and other renewable resources to recover electric energy or hydrogen energy with low energy consumption and have gained a growing interest.This process has several advantages over other biohydrogen processes,such as high hydrogen yields and the ability to use many different types of substrata including fermentable and non-fermentable organics.However,cathode catalysts for the hydrogen evolution reaction put forward a major challenge for the development and future applications of MEC.An ideal cathode catalyst should be catalytically active,simple to synthesize,durable in a complex environment,and cost-effective.Nano zeolites are widely used in the field of catalysis and adsorption owing to their large surface area,short diffusion path and easy exposure of active sites.In this paper,nano-Y zeolites were synthesized by adding carbon spheres templet into the non-directing agent system,and the nano-Ni O-Y composite zeolites cathode hydrogen evolution material was prepared by using nano-Y zeolites as carrier,which was used in microbial electrolysis cell to evaluate the hydrogen evolution performance.The results showed that,when m（CSs）/m（Si O₂）=0.45,the aging time was 6 d,the composites with 500 nm of size not only possess nano particle structure,but also exhibited a type of multiple porous structure including microporous and mesoporous.The total surface area and volume of nano-Ni O-Y composites were 774.3 m²?g^-1and 0.495 cm³·g^-1,respectively.Electrocatalytic hydrogen evolution activity of nano-Ni O-Y3composite catalyst was investigated by linear scan（LSV）,tafel plot and electrochemical impedance spectroscopy（EIS）.The results showed that when the nickel salt loading was 30 wt%,the current response value of LSV was higher,and the EIS as well as Tafel plots（48.41 m V/dec）outperforms Pt/C and CP,indicating that the charge transfer rate was faster;the proper amount of supported nickel catalyst exposed more active sites.Further,the nano-Ni O-Y3composite catalyst had high electrocatalytic hydrogen evolution activity.In a continuous operation cycle,the largest hydrogen evolution current density of the nano-Ni O-Y composites reached 22.87 A·m^-2,and H₂content was about73.71±0.95%in total gas production,hydrogen production rate was 0.393±0.04m³/m³d,comparable to the hydrogen production efficiency of Pt/C cathode.The porous material has a large specific surface area and a rich pore structure,which can provide more active sites and increase the electrocatalytic rate.Therefore,loading the nickel-based catalyst into the micro-mesoporous composite zeolites can greatly improve the catalytic hydrogen evolution ability of the MEC cathode and prolong the life of the catalyst.In this paper,micro-mesoporous MCM-41/Y composite zeolites were prepared by ion exchange method and nano-assembly method,respectively.The effects of two synthetic methods on the morphology and texture of composite zeolites were discussed.The micro-mesoporous Ni-MCM-41/Y composite zeolites catalyst was prepared by using the synthetic samples as the carriers,and they were used for hydrogen production in MEC to evaluate their catalytic hydrogen evolution performance.The results showed that Samples A synthesized by ion exchange method were mainly embedding type,and Samples B synthesized by nano-assembly method were epitaxial growth and self-assembly.Specific surface areas were 665.1 m²·g^-1and 0.6438 cm³·g^-1,respectively.The total pore volume was 0.6438 cm³·g^-1and 0.6529 cm³·g^-1,respectively.The specific surface area of the sample B was more significant than that of the pure Y zeolites,which was increased by about 2.4 times.This indicated that the surface charge and aggregation ways of the two synthetic systems had a certain influence on the morphology,specific surface area and pore structure of the composite zeolites.Electrochemical tests of linear scanning voltammetry showed that the Samples B2 composite exhibited the best catalytic activity for hydrogen evolution reaction as a MEC cathode.In the MEC tests,The peak current density of the Samples A1 and Samples B2 cathode was 162.8 A·m^-2and188.3 A·m^-2,respectively,which were significantly higher than the CP cathode.The coulombic efficiency,cathodic energy efficiency rate and hydrogen production rate obtained with the Samples B2 cathode MEC were 85.9±6.2%,228.4±18.6%and 0.83±0.05 m³/m³d,respectively,which were slightly higher than those obtained with the Samples A1 cathode.This further demonstrates that the Samples B2 composite zeolites exhibited an effective hydrogen evolution reaction activity.