Palladium Nanoparticles with Surface Enrichment of Palladium Oxide Species Immobilized on the Aniline-Functionalized Graphene As an Advanced Electrocatalyst of Ethanol Oxidation

Abstract

A new electrocatalyst (denoted as Pd-PdO x /GS-NH2) was fabricated by anchoring Pd nanoparticles with surface enrichment of palladium oxide species (PdO x , including palladium oxides and palladium hydrous oxides) on the aniline-functionalized graphene (GS-NH2) in this work. The GS-NH2 with tunable contents of aniline groups was prepared by a diazo reaction under facile reaction conditions. Then, the surface-clean Pd nanoparticles were decorated on the surface of GS-NH2 by a facile and nonsurfactant approach. Afterward, the palladium oxide species was introduced on the surface of Pd nanoparticles by oxidation treatment in a short period of time. As a catalyst toward the ethanol electrooxidation reaction (EOR), Pd-PdO x /GS-NH2 displays the introduction of appropriate aniline groups and an oxidation treatment with a codependent electrochemical behavior of EOR, mainly owing to the synergy of aniline groups and PdO x . The introduction of aniline groups on the surface of graphene benefits the formation of small size and uniform distribution for nanoparticles and suppresses the dissolution of Pd during electrochemical tests, due to the strong interaction between aniline groups and nanoparticles. However, the excess contents of aniline groups can reduce electrical conductivity of the catalysts, and the optimal mass ratio of 1,4-diaminobenzene to graphene is 1:3. The generated PdO x can strikingly facilitate the removal of COads-like intermediates and elimination of poisoning species during the EOR process, thereby reducing the degradation rate of the catalyst. Therefore, the Pd-PdO x /GS-NH2 possesses superb EOR performance with robust durability and is a kind of great potential anode catalyst for direct ethanol fuel cells. This work also affords a new thought for rationally designing high-performance catalysts.

Recent advances in graphene‐based materials for fuel cell applications

“…Modification of graphene with heteroatom and functional groups provides more anchor sites for metal nanoparticles, which largely promote EOR activity and durability 131,132 . Yang et al 131 prepared aniline‐functionalized graphene by a diazo reaction to anchor Pd nanoparticles for EOR.…”

“…Modification of graphene with heteroatom and functional groups provides more anchor sites for metal nanoparticles, which largely promote EOR activity and durability 131,132 . Yang et al 131 prepared aniline‐functionalized graphene by a diazo reaction to anchor Pd nanoparticles for EOR. The mass activity after the 7200 seconds test of the catalyst with aniline groups (43.1 mA mg −1 ) was about 5 times higher than that (8.9 mA mg −1 ) without aniline modification, which was attributed to the highly distribute Pd nanoparticles and the strong interaction between aniline groups and Pd.…”

High Active PdSn Binary Alloyed Catalysts Supported on B and N Codoped Graphene for Formic Acid Electro-Oxidation

“…Particularly, functionalizing or heteroatom doping into the graphene architectures can easily tune the electronic structures and improve the electrochemical reactivity [22,23]. Many research groups have made efforts to synthesize doped graphene as metal supports for enhancing the electrocatalytic performance toward the electro-oxidation of alcohol and formic acid [24][25][26].…”

“…However, the synergistic effect of PdSn alloys and functional and/or doped graphene nanocomposites still needs to be illuminated. Morever, recent studies showed that dual-doped graphene can combine the advantages of two different heteratoms and lead to further enhanced catalytic performance [24]. In this work, a series of PdSn bimetallic catalysts supported on B-N dual-doped graphene is prepared by a chemical reduction method, and their electrocatalytic properties on the electro-oxidation of formic acid are investigated.…”

In situ formation of surface and bulk oxides in small palladium nanoparticles

“…Palladium-based materials are extensively investigated as catalysts for a wide range of important industrial reactions, such as methane combustion [1][2][3][4] and selective oxidation of alcohols. [5][6][7] Palladium oxide is generally considered to be the actual catalytic species in many of these reactions, however, the activity of metallic palladium or core-shell combinations of Pd and PdO were also reported. [8][9][10] A number of previous studies highlighted the importance of in situ detection of palladium oxides and their distribution in the bulk and at the surface of palladium particles to highlight the actual active phase in catalytic oxidation reactions.…”