High Electrocatalytic Activity of Pt/C Catalyst Promoted by TT-Nb2O5 Nanoparticles under Acidic Conditions

摘要

Methanol electrooxidation activity of pseudohexagonal niobium pentoxide (TT-Nb2O5) nanoparticles promoted Pt/C catalyst under acidic conditions is reported. The TT-Nb2O5 nanoparticles (nano-TT-Nb2O5) with crystallite size ~22 nm were prepared by sol-gel approach and incorporated into Vulcan carbon by a solid state intermittent microwave heating method. Subsequently, Pt nanoparticles were deposited over the TT-Nb2O5/C composite by conventional polyol reflux method. It is found that the TT-Nb2O5 promotes Pt particle dispersion and the average size of Pt nanoparticles thus obtained is about 3.2 nm. The electrochemical methanol oxidation studies were performed on Pt/nano-TT-Nb2O5/C catalyst and compared with bulk-orthorhombic niobium pentoxide (bulk-T-Nb2O5) promoted Pt/C as well as bare Pt/C catalysts. The electrooxidation results show that the nano-TTNb2O5 promoted Pt/C catalyst exhibits lower onset potential and higher current density compared to Pt/bulk-T-Nb2O5/C and Pt/C catalysts. Also, it has shown appreciable catalytic stability and improved antipoisoning ability during the methanol oxidation. The origin of higher electrocatalytic activity of Pt/ nano-TT-Nb2O5/C catalyst is attributed to the large number of triple-phase interface active centers on nano-TT-Nb2O5, which provide abundant hydroxide (OH-) species for effective oxidation of intermediates such as adsorbed carbon monoxide (COads) at lower potentials.