Progress and perspectives on the development of anti-CO poisoning electrocatalysts in hydrogen fuel cells
Platinum(Pt)is usually used to catalyze the hydrogen oxidation reaction(HOR)on the anode side of hydrogen fuel cells.However,current industrially-produced hydrogen(H2)as the main source of anode feed gas inevitably contains a small amount of carbon monoxide(CO)as the main impurity,leading to the reduced activity of Pt electrocatalysts due to CO poisoning.Therefore,improving the anti-CO poisoning ability of anode electrocatalysts is now a major challenge in the field of HOR studies.This review first focuses on the current status of the most prevalent Pt-based HOR electrocatalysts with regard to the three main synthetic strategies for improving the anti-CO poisoning ability.Via metal doping or promoted CO oxidation via oxide doping,doping Pt-based electrocatalysts with transition metals or metal oxides usually leads to reduced CO adsorption.Surface modification of catalysts,including the construction of core-shell structures,the design of special surface morphologies,and the addition of surface-regulated organic molecules,can usually enhance the activity and selectivity toward HOR while inhibiting the poisoning process on the surface.Support modification or selection,including carbon black modification and support replacement with other types of carbon or metal oxides,normally makes use of the interaction between supports and metal particles to reduce the influence of CO poisoning with similar or even improved HOR activities.All these applied strategies aim to introduce an electronic or bifunctional effect to either weaken the CO adsorption or facilitate the CO oxidation and are also adopted to guide the development of other types of HOR electrocatalysts.Then,progress related to other types of non-Pt HOR electrocatalysts,including other platinum group metal(PGM)electrocatalysts and non-noble metal electrocatalysts,has been introduced successively.Other PGM electrocatalysts have stable chemical properties,and some of them even have better anti-CO poisoning abilities.The investigation of the origin of their intrinsic anti-CO poisoning abilities will definitely help improve the Pt-based electrocatalysts,as other PGM metals may have lower HOR activities and higher costs than Pt.The main motivation for non-noble metal electrocatalysts is to drastically reduce the anode cost.Some progress has been made,but there is still a long way to go before non-noble metal electrocatalysts can replace Pt-based electrocatalysts.In the end,perspectives for the future development of anti-CO poisoning electrocatalysts for HOR have been proposed.The ultimate goal for developing HOR electrocatalysts is to achieve high HOR activity with good CO tolerance,high stability,and low cost on the premise of ensuring HOR activity and overcoming the influence of CO poisoning.Nowadays,it is not enough to use just a single strategy to improve both the HOR performance and the anti-CO poisoning ability.Future studies will focus on multiple synthetic strategies to maximize the influence of the electronic effect and the bifunctional effect at the same time to explore better Pt-based electrocatalysts and also seek the possibilities of the real application of non-Pt electrocatalysts.
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