Enhancing the Electrocatalytic Activity of Pd/M (M = Ni, Mn) Nanoparticles for the Oxygen Reduction Reaction in Alkaline Media through Electrochemical Dealloying

Abstract

We have developed a facile and effective electrochemical dealloying strategy to enhance the electrocatalytic activity of Pd/M (M = Ni, Mn) nanoparticles for the oxygen reduction reaction (ORR) in alkaline media. The enhancement arises from the higher atomic concentration of electrochemically active Pd exposed on the surface of the nanoparticles as a result of the electrochemical dealloying process, which was verified by electron energy loss spectroscopy elemental mapping, X-ray photoelectron spectroscopy, and CO stripping. These dealloyed catalysts also showed a negligible decrease in the ORR activity after 4000 potential cycles in alkaline media. In addition, after the degradation that resulted from extended potential cycles in alkaline media, the ORR activity of the catalysts could be restored by repeating the dealloying procedures, with only a 14 mV decrease in the half-wave potential after 16,000 cycles for dealloyed PdNi/C. Similar results were obtained for PdMn/C. These findings provide insights for the rational design of the composition and structure of electrocatalysts with higher atomic utilization of active materials and enhanced electrocatalytic activity, based on postsynthesis modification methods.

A CoV2O4 precatalyst for the oxygen evolution reaction: highlighting the importance of postmortem electrocatalyst characterization

“…This process is qualitatively similar to electrochemical dealloying previously used to make porous battery materials and catalysts. [28][29][30][31][32][33] We postulate that the increased observed activity for our catalyst compared to Co 3 O 4 may be due in part to an increased surface area after V-dissolution. Unfortunately, we were not able to harvest sufficient amounts of material post-CCE for BET gas adsorption measurements.…”

Unravelling charge-transfer in Pd to pyrrolic-N bond for superior electrocatalytic performance

“…[1][2][3][4] Recent investigations have shown that the electrocatalytic efficiency of the Pdbased catalysts can be improved systematically and significantly to match those of Pt by adopting innovative design strategies, tailoring their surfaces by means of facet engineering or alloy formation and tuning of substrate-catalyst interactions. [5][6][7][8][9][10][11] However, two outstanding challenges in AFCs while using Pd nanocrystals (NCs) remain to-date: i) overcoming the sluggish ORR kinetics to further reduce the Pd requirement to match a target set by U.S. Department of Energy, and ii) the absence of sustained highcatalytic activity for prolonged time-periods under the electrochemical operating environments. 6,8,12 Therefore in the existing device prototypes, a larger amount of noble metal is loaded on to the electrode surfaces to attain a sufficient durability.…”

“…has emerged as a preferred strategy to modulate the surface electronic structure for improved catalytic activity, and to reduce the noble metal load at the same time. [7][8][9][11][12][13][14][15] The electrons in the 'other' metals hybridize with the d electrons of Pd to lower the 'd-band center' effecting a favorable modulation of the bond-strengths of the ORR intermediates. 16,1718 Besides, the lattice strain invoked by smaller sizes of the alloying atoms also helps in attenuating the intermediate binding energies.…”

“…1,9,21 Another general disadvantage in using alloys may arise due to a continuous change of their compositions during catalysis due to the high chemical reactivity of the non-noble components. 11 On the other hand, extremely high stability up to 100000 cycles was achieved recently by using alloy thin-films, but even the initial activities were poorer than the deactivated performances of the nanoparticulate catalysts due to a larger catalyst load. 13 Alternatively, it has long been predicted that metal to substrate charge-transfer interactions (MSI) can be used for regulating the metal-oxygen bond-strengths [22][23][24] and was demonstrated experimentally using various substrates such as sp 2 carbon derivatives recently for improved ORR activity.…”

Palladium Nanoparticles Supported on Cellulosic Paper as Multifunctional Catalyst for Coupling and Hydrogenation Reactions

“…In addition, their pseudo‐homogeneous behavior in solution owing to the nano‐sized dimension (<10 nm) combined with the advantages of a heterogeneous catalyst by supporting on a solid make them perfect candidates for potential industrial applications. Within this context, a large variety of highly productive catalysts based on nanoparticles of Co, [1,2] Mn, [3,4] Rh, [5,6] Ir, [7,8] Pd, [9,10] and Pt [11,12] have been developed for catalytic organic transformation reactions. Among these nanoparticles, Pd metal nanoparticles (PdNPs) have proven to be the most powerful catalyst for many organic syntheses of industrial importance, such as the synthesis of pharmaceuticals, medicines, pesticides, degradation of organic pollutants, C−C bond formation and the hydrogenation reaction [13] .…”