Designed Formation of Hollow Pt Nanocrystals Supported on MoO_x-Modified Carbon for High-Performance Methanol Electro-Oxidation

Abstract

In this study, we develop an efficient electrocatalyst for methanol oxidation, Pt nanocrystals (NCs) with hollow structure immobilized on MoO x -modified carbon black (h-Pt/MoO x -C). The MoO x -C is fabricated by phosphomolybdic acid self-assembly on carbon black. The h-Pt/MoO x -C evolved from Ag@Pt core−shell NCs deposited on MoO x -C in saturated NaCl aqueous solution containing NH 4 OH. Because of the presence of MoO x , the electrocatalyst of solid Pt NCs anchored on MoO x -C (Pt/MoO x -C) for methanol oxidation exhibits about 3.4 times higher electrocatalytic activity than solid Pt NCs anchored on carbon black (Pt/C−H). The mass activity of h-Pt/MoO x -C is 2.4 times greater than that of Pt/MoO x -C, ascribing to the unique hollow structure. Furthermore, the h-Pt/MoO x -C also exhibits better tolerance to poisoning species and is more stable under electro-oxidation conditions.

Electronic and Coordination Effect of PtPd Nanoflower Alloys for the Methanol Electrooxidation Reaction

“…Abundant OH* species provided by adjacent metal sites assist in the dehydrogenation and oxidation of intermediates and quickly remove these intermediates to release Pt active sites, thus continuously promoting the further oxidation of methanol. 9,10 Tremendous efforts have been made on Pt-based catalysts to control the compositions 11,12 and nanostructures 13,14 for enhancing MOR performance, including alloy engineering, 15,16 Pt/metal oxide, 17 Pt/substrate interactions, 18 even non-Pt materials, 19 and diverse specific shapes (nanoflowers, nanowires, nanosheets, etc.). 20,21 Among them, the alloy strategy has received increasing research interest due to the minimization of poisoning effects and greatly enhanced MOR performance, 22 which depends on the specific properties of the additional metal.…”

Pt3Sn nanoparticles enriched with SnO2/Pt3Sn interfaces for highly efficient alcohol electrooxidation

“…30 The design of interfacial Pt-metal oxides structures in DAFCs anode catalytic systems is believed to be another effective strategy. [31][32][33][34] The interfacial Pt-metal oxides structures not only improve the stability resulting from the strong metal-support interaction (SMSI) effect, but also improve the Pt activities through bifunctional mechanism, wherein metal oxides provide adsorbed hydroxyl groups for adjacent Pt active sites to facilitate the oxidation and removal of the reaction intermediates (e.g., CH x and CO) at a lower potentials and thus improve the Pt activities towards MOR and EOR. 35 For examples, SnO 2 NPs were widely used to provide hydroxyl groups for helping removal of adsorbed CO on the surface of Pt, leading to improved electrocatalytic performance for methanol/ethanol oxidation.…”

Highly Porous Pt2Ir Alloy Nanocrystals as a Superior Catalyst with High-Efficiency C–C Bond Cleavage for Ethanol Electrooxidation

“…1−3 Up to now, methanol is regarded as the most advanced liquid fuel among direct liquid fuel cells because of its simple chemical structure and high energy density (6.09 kWh kg −1 ). 4,5 However, methanol is toxic to humans and easily permeates through Nafion membranes, which severely restrict its practical application in fuel cells. Ethanol, as a renewable energy source, can replace methanol as the preferred fuel for DLFCs because of its many merits that methanol does not have, such as nontoxicity, high energy density (8.03 kWh kg −1 ), abundant sources, and low Nafion membrane permeability.…”

“…Direct liquid fuel cells (DLFCs) fueled by liquid fuels are receiving more and more attention in the field of portable transportation power. Compared with hydrogen fuel cells, they have advantages such as a wide array of fuel sources, higher mass density, safer operation, lower operating cost, simpler equipment structure, and so on. − Up to now, methanol is regarded as the most advanced liquid fuel among direct liquid fuel cells because of its simple chemical structure and high energy density (6.09 kWh kg –1 ). , However, methanol is toxic to humans and easily permeates through Nafion membranes, which severely restrict its practical application in fuel cells. Ethanol, as a renewable energy source, can replace methanol as the preferred fuel for DLFCs because of its many merits that methanol does not have, such as nontoxicity, high energy density (8.03 kWh kg –1 ), abundant sources, and low Nafion membrane permeability. − Therefore, the direct ethanol fuel cell (DEFC) using ethanol as fuel not only has theoretical research value but also has great practical application potential. , Nevertheless, the current DEFC performance is low and difficult to commercialize, which is mainly owing to the slow kinetics of the ethanol oxidation reaction (EOR). , It is generally believed that EOR involves two parallel pathways, the partial oxidation pathway that produces acetic acid (CH 3 COOH) and acetaldehyde (CH 3 CHO) and the complete oxidation pathway that acquires a maximum fuel utilization efficiency through C–C bond cleavage. − A big challenge in the commercialization of DEFC is to explore highly active yet stable electrocatalysts to break the C–C bond to accomplish complete ethanol oxidation. , …”