Enhanced Electrocatalysis of Oxygen Reduction on Pt/TaO_x/GC

Abstract

Here we demonstrate a remarkable enhancement of oxygen reduction reaction (ORR) activity on a novel Pt/TaO x /GC electrocatalyst where at first tantalum oxide (TaO x ) and next Pt were deposited electrochemically on a glassy carbon (GC) surface. An excellent electrocatalytic activity of the Pt/TaO x /GC electrocatalyst for ORR was found to be more than 12 times that of the unmodified Pt/GC one as evaluated from the kinetic currents at 0.80 V. SEM images showed no significant differences in the size and distribution of Pt nanoparticles between these two electrocatalysts, indicating that these are not factors causing the observed ORR activity. The spillover of oxygen-containing species resulting from the electronic interaction between Pt and TaO x , which is evidently demonstrated from the XPS analysis, is strongly suggested as the crucial factor for the ORR enhancement. Interestingly, the spillover effect also results in a remarkable increase in the electrochemically active “apparent” surface area of Pt on the Pt/TaO x /GC electrocatalyst. Moreover, the rotating ring-disk electrode voltammetric measurements obviously showed the increase in limiting current as well as the decrease in ring current on this novel electrocatalyst relative to the unmodified one, confirming a complete four-electron reduction pathway. On the basis of these findings a plausible mechanism has been proposed for the observed enhancement in ORR where the role of TaO x is to reduce the formation of OH on the Pt surface by spillover effect and to promote d orbital vacancy of Pt for oxygen adsorption by electron donation to Ta.

Electrochemical oxygen reduction behaviour of platinum nanoparticles supported on multi-walled carbon nanotube/titanium dioxide composites

“…Therefore a great number of alternative catalyst support materials have been proposed in recent studies [4][5][6]. A great deal of attention has been paid to metal oxides, in particular TiO 2 , SnO 2 , Nb x O y , WO 3 , MnO x , Ta 2 O 5 [7][8][9][10][11][12][13][14][15][16][17][18][19]. In recent years, intensive research has been focused on the investigation of TiO 2 as a potential candidate support material in the form of nanoparticles, nanotubes or combined with different carbon materials forming a multi-component composite support structure for catalytic nanoparticles [20][21][22][23][24][25][26][27][28][29].…”

An XPS depth-profile study on electrochemically deposited TaO x

“…In heterogeneous catalysis, Ta 2 O 5 has been long used as an alloy addition that improves lifetime, selectivity, and activity of other oxide catalysts [3,4]. In light of the recent need to develop highly efficient materials to replace the conventional Pt/C catalyst at the electrodes of polymer electrolyte membrane fuel cells, TaO x has gradually seen increased applications as a metal support for noble metals [5][6][7][8][9][10]. In light of the recent need to develop highly efficient materials to replace the conventional Pt/C catalyst at the electrodes of polymer electrolyte membrane fuel cells, TaO x has gradually seen increased applications as a metal support for noble metals [5][6][7][8][9][10].…”

“…In light of the recent need to develop highly efficient materials to replace the conventional Pt/C catalyst at the electrodes of polymer electrolyte membrane fuel cells, TaO x has gradually seen increased applications as a metal support for noble metals [5][6][7][8][9][10]. As a metal support, TaO x , through a phenomenon, often termed as a strong metal-support interaction, has been demonstrated to significantly improve the performance of platinum as ORR electrocatalyst (by up to 12 times) [7]. As a metal support, TaO x , through a phenomenon, often termed as a strong metal-support interaction, has been demonstrated to significantly improve the performance of platinum as ORR electrocatalyst (by up to 12 times) [7].…”

Enhancement of the electrocatalytic oxygen reduction reaction on Pd3Pb ordered intermetallic catalyst in alkaline aqueous solutions

“…The electronic interaction between Pd and TiO 2 via the Ti-O-Pd bridging, as mentioned in the XPS results, contributes to the enhancement of ORR with the following two factors: (1) OH adsorbed on the Pd surface in the Pd 3 Pb NPs is spilled over to the TiO 2 (reduction of the formation of OH on the Pd surface) [46,47] and (2) the d orbital electron in the Pd atoms is donated to Ti atoms through the bridging Ti-O-Pd bond (d orbital vacancy, resulting in enhanced 2p electron donation from [47,48], both of which facilitate O 2 adsorption on the Pd surface, that is, the first step of the ORR, to rapidly produce two desirable H 2 O molecules.…”