Porous Pd‐PdO Nanotubes for Methanol Electrooxidation

Abstract

Palladium (Pd) nanostructures are highly active non-platinum anodic electrocatalysts in alkaline direct methanol fuel cells (ADMFCs) and their electrocatalytic performance relies highly on their morphology and composition. Herein, a facile high-temperature pyrolysis method to synthesize high-quality Pd-palladium oxide (PdO) porous nanotubes (PNTs) by using Pd(II)-dimethylglyoxime complex (Pd(II)-DMG) nanorods as a selftemplate is reported. The chemical component of pyrolysis products highly correlates with pyrolysis temperature. The electrochemical measurements and density functional theory calculations show the existence of PdO enhances the electroactivity of metallic Pd for both methanol oxidation reaction (MOR) and carbon monoxide oxidation reaction in alkaline media. Benefiting from its one-dimensionally porous architecture and evident synergistic effect between PdO and Pd (e.g., electronic effect and bifunctional mechanism), Pd-PdO PNTs achieve a 3.7-fold mass activity enhancement and improved durability for MOR compared to commercial Pd nanocrystals. Considering the simple synthesis, excellent activity, and long-term stability, Pd-PdO PNTs may be highly promising anodic electrocatalysts in ADMFCs.optimal chemical component and structural advantage, Pd-PdO PNTs with optimal component revealed eminent electrocatalytic activity and durability for MOR in alkaline medium.

Bifunctional Pd‐CeO2 Nanorods/C Nanocatalyst with High Electrochemical Stability and Catalytic Activity for the ORR and EOR in Alkaline Media

“…It is also likely that surface oxides such as PdO catalyze the reaction. This species promotes the catalytic activity of Pd nanocatalysts for the oxidation of organic molecules, as concluded from the findings by Sawangphruk et al, [53] Chen et al, [54] and Manzo-Robledo et al [55] It has been suggested that Pd-oxides limit the poisoning effect of adsorbed carbonaceous species by forming OH À species. As concluded from XPS analysis, Pd-CeO 2-NR /C forms more PdO species than Pd/C, positively affecting its catalytic behavior.…”

Low‐Dimensional Metallic Nanomaterials for Advanced Electrocatalysis

“…[71] To date, a variety of heterogeneous interfaces have been created for boosting electrocatalytic reactions, such as metal-metal, metal-metal oxide, and metal-metal sulfide interfaces. [72,73] Regarding the metal-metal interface, core-shell-type nanomaterials have been acknowledged as promising catalysts for electrochemical reactions. The lattice mismatch between the inner core and outer shell could induce lattice strain on the surface of nanomaterials.…”

“…[ 71 ] To date, a variety of heterogeneous interfaces have been created for boosting electrocatalytic reactions, such as metal–metal, metal–metal oxide, and metal–metal sulfide interfaces. [ 72,73 ]…”

“…A representative example was the Pd–PdO heterostructure, which was designed and fabricated by Chen and coworkers to work as an advanced electrocatalyst for MORs. [ 72 ] Specifically, Pd–PdO porous nanotubes (PNTs) were prepared by pyrolyzing Pd(II)–dimethylglyoxime complex (Pd(II)–DMG) nanorods ( Figure a–d). Interestingly, the unique 1D porous and hollow nanostructure endowed the Pd–PdO PNTs with high ECSA, facilitated mass and electron transfer, and gave them high mechanical stability.…”

“…Reproduced with permission. [ 72 ] Copyright 2020, Wiley‐VCH. e–g) HRTEM, h) TEM, i) HAADF‐STEM, and j) EDS elemental mapping images of Pt 3 Ni 3 –S nanowires.…”