Design Of Pt-Based Catalyst For Fuel Cell And Its Oxygen Reduction Reaction Activity

The development of fuel cells in the efficient and low cost cathode oxygen reduction?ORR?electrocatalyst is a long-standing hot topic.The slow kinetics of cathodic oxygen reduction in fuel cells results in a high demand for Pt on cathode catalysts.However,the current shortage of Pt resources and the high cost of Pt to reduce the amount of use,the contradiction between the two impeded the commercial use of fuel cells.Development of high specific surface area,the structure of the controllable Pt alloy electrode is one of the effective ways to solve the above problems.In the long run,in order to realize the large-scale application of fuel cells,it is necessary to find non-noble metal catalysts with high catalytic activity for ORR or high activity catalysts with low platinum loading to replace or reduce the use of Pt as the fundamental way to reduce the cost of PEMFC.?1?This chapter the Metal-Organic Framework?MOF?was used as template to synthesize ORR catalyst for ordered low Pt loading PEMFC.Pt nano-particle was embedded into the internal pores of MOFs by impregnation method.After heat treatment,a platinum-doped nitrogen-doped polyhedral mesoporous carbon material was obtained.The morphology,composition and structure of the catalyst were characterized by XRD,SEM,TEM and XPS;The electrochemical method was used to test the oxygen reduction performance of the synthesized ordered low Pt loading catalyst;The catalyst was evaluated for its stability and durability by accelerating durability.The catalyst gained heat treated at 900°C has the best oxygen reduction performance.At 0.85V vs RHE,the mass activities was estimated to be 49.43mA mg_Pt^-1,which is 14.18 mA mg_Pt^-1 highter than the commercial catalyst.The half-wave potential is 11 mV higher than commercial commercial catalyst,and the stabilization in acidic electrolytes is also superior to commercial Pt/C catalyst.After durability test of 1000 cycles,the half-wave potential of the Pt/Co-NC-900 catalyst only decreased15 mV,while the commercial Pt/C catalyst was decreased 47 mV.?2?Rapid room-temperature synthesis of octahedral metal-organic framework HKUST-1 crystals as precursor.The MOF was encapsulation in NaCI by salt seal method.After high temperature pyrolyzed,used the acid solution to removing the metal,an ordered mesoporous carbon support with a regular octahedral morphology was prepared.The Pt nano-particles were loaded into the prepared carbon support by a colloid method,a high activity catalyst with low platinum loading was obtained.The structure,composition and morphology of the catalyst were analyzed by XRD,SEM,XPS and TG-DSC,and its electrochemical catalytic performance and durability were tested and analyzed.The results show that the half wave potential and durability of Pt/OPC-700 are significantly higher than those of commercial Pt/C catalyst.The stability mechanism of Pt/OPC-700 was analyzed and it was considered that the encapsulation and steric hindrance of OPC effectively enhanced the stability of the catalyst.?3?A highly efficiency and durability Pt/GC catalyst was synthesized by Sol-Gel method used the graphitized-carbon as support.The structure and composition of the Pt/GC catalyst was characterized by XRD,TEM,Raman and XPS.The result shows that the size of Pt nanoparticles in the catalyst is 2-3 nm,and the distribution is very uniform.Moreover,this low Pt catalyst with graphitized carbon as support exhibited the high catalytic activity and long durability:the half-wave potential of the Pt/GC catalyst only decreased 10mV after 1000 cycles durability test.