Preparation Of Co-based Naphthol Composite And Its Catalytic Performance In Oxygen Reduction Reaction

Due to the benefit of high conversion efficiency and pollution-free product,fuel cell is called as the most promising energy conversion device.The oxygen reduction reaction that reacted in the cathode is the important part of fuel cell,but the reaction process is slow which needs electrocatalyst to catalyze.The platinum based electrocatalysts which is the best one in today don’t commercialise due to the high price,resource scarcity and easy poisoning in the methanol.Therefore,development of the electrocatalysts with low cost,high efficiency and methanol resistance is a hotspot.The purpose of this paper is to develop a transition metal chelate catalyst with high catalytic activity that naphthol is used as the raw material of ligands to prepare naphthol cobalt（Co-NOL）.Naphthol is a common chemical raw material with moderate price which is used as a reagent for cobalt removal in zinc hydrometallurgy with mature preparation process.In this paper,Co-NOL was synthesized from naphthol and cobalt nitrate.The Co-NOL was modified with urea and melamine as nitrogen source in the ethanol solution.The microstructure and internal structure of the material were analyzed by means of XRD,XPS,SEM,FI-IR,Raman.The electrochemical performance and methanol resistance of the materials were studied by electrochemical measurement.The results of the study are as follows:The XRD of Co-NOL showed that the Co-NOL material was amorphous.It was observed and anslysised from the miscrostructure that Co-NOL particle size was about 100 nm with nitroso,naphthol and Co-O groups.In electrochemical testing,Co-NOL showed ORR catalytic performance and methanol resistance,its onset potential was-0.184V（vs.Hg/HgO）.With carbon black support,its onset potential reached-0.053V（vs.Hg/HgO）,and the limit current density was up to 3.97 mAcm^-2.In the catalytic process,Co-NOL was in the 4 electrons way to reaction.The morphology of Co,CoO and Co₃O₄ was characterized by XRD of doping urea naphthol cobalt（Co-NOL@U）,which was consistent with the results of XPS analysis.Raman results showed that the A_G/A_D of Co-NOL@U was higher than that of Co-NOL,indicating that the graphitization of carbon layer was more obvious.In electrochemical tests,the onst potential of Co-NOL@U was-0.03V（vs.Hg/HgO）,and the limit current density was 2.57 mAcm^-2.After adding carbon black in the heat treatment process,the electrochemical performance was greatly improved,the onset potential was-0.007V（vs.Hg/HgO）,and the limit current density was as high as 3.98mAcm^-2.In the catalytic process,Co-NOL@Urea was in the 2 electrons and 4electrons ways to reaction.The results of XRD and Raman analysis of doping melamine naphthol cobalt（Co-NOL@M）were similar to those of Co-NOL@U.In the electrochemical test,Co-NOL@M showed ORR catalytic performance and methanol resistance,its onset potential is-0.01V（vs.Hg/HgO）,and the limit current density was 3.01mAcm^-2.After carbon black was added to the heat treatment process,the onset potential shifted positively to 0.031V（vs.Hg/HgO）,and the limit current density reached 4.73 mAcm^-2,which was similar to 20%commercial Pt/C.The reaction mechanism of Co-NOL@M was carried out in the way of 2 electrons and 4 electrons migrate together.In a word,it has an important application prospect that naphthol is used as the raw material to prepare the transition metal chelates as the ORR electrocatalyst for fuel cells.It opens up a new way for the exploration of the catalyst for ORR,and lays a foundation for the commercial application of the fuel cell as soon as possible.