MXene Surface Terminations Enable Strong Metal–Support Interactions for Efficient Methanol Oxidation on Palladium

Abstract

Efficient catalysis of the methanol oxidation reaction (MOR) greatly determines the widespread implementation of direct methanol fuel cells. Exploring a suitable support for noble metal catalysts with regard to decreasing the mass loading and optimizing the MOR activity remains a key challenge. Herein, we achieve an over 60% activity enhancement of a palladium (Pd) catalyst by introducing a two-dimensional Ti3C2T x MXene as the support compared to a commercial Pd/C catalyst. Not only are more catalytically active Pd sites exposed on the Pd/MXene catalyst while maintaining a low mass loading, but the introduction of the MXene support also significantly alters the surface electronic structure of Pd. Specifically, spectroscopy and density functional theory (DFT) computations indicate that sufficiently electronegative terminations of the Ti3C2T x MXene surface can induce strong metal–support interactions (SMSI) with the Pd catalyst, leading to optimal methanol adsorption. This MXene-supported Pd catalyst exhibits a much higher MOR current density (12.4 mA cm–2) than that of commercial Pd/C (7.6 mA cm–2). Our work largely optimizes the intrinsic activity of a Pd catalyst by the utilization of MXene surface terminations, and the crucial SMSI effects revealed herein open a rational avenue to the design of more efficient noble metal catalysts for MOR.

Recent Progress in MXene‐Based Materials: Potential High‐Performance Electrocatalysts

“…Reproduced with permission. [26] Copyright 2020, American Chemical Society. activity of Pt/Ti 3 C 2 MXene can be assigned to the unique stable 2D nanosheet structure, excellent electric conductivity, strong binding strength as well as electronic effect between Pt and Ti 3 C 2 MXene.…”

“…Lang et al [26] have demonstrated an over 60% activity enhancement of Pd catalysts toward MOR through the introduction of an MXene support with rich surface terminations. The prepared Pd/MXene has a high MOR activity of 12.4 mA cm −2 , which is superior to commercial Pd/C (7.6 mA cm −2 ).…”

Tuning 2D MXenes by Surface Controlling and Interlayer Engineering: Methods, Properties, and Synchrotron Radiation Characterizations

“…Besides the wide applications of MXenes and MXene‐based materials on the above electrochemical energy storage devices, MXenes have been considered as promising candidates of photocatalysis and especially electrocatalysis including HER, [ 118 ] N 2 reduction reaction (NRR), [ 119 ] OER, [ 120 ] oxygen reduction reaction (ORR), [ 121 ] CO 2 electroreduction (CO 2 RR), [ 122 ] and ethanol oxidation [ 123,124 ] Generally, the electrocatalysis property was highly depended on the functional groups. Such as, in 2017, it was reported that F‐termination would hinder the HER performance of Mo 2 CT x and oxygen groups on the basal planes of Mo 2 CT x were catalytically active toward the HER.…”

Strategies for Fabricating High‐Performance Electrochemical Energy‐Storage Devices by MXenes

“…As mentioned in section 2, chemical etching is currently the most popular approach to synthesise MXenes and has a considerable impact on the type and the content of surface terminations. [160] The influence of surface functional groups on the electrochemical performance of MXenes was studied by Hu et al, in which Ti 3 C 2 T x MXenes were prepared by aqueous HF acid with two various concentration levels (6 M and 15 M). [30] It was revealed by in situ Raman spectroscopy that Ti 3 C 2 T x prepared with 6 M HF etching (Ti 3 C 2 T x -6 M) contained more À O terminations than 15 M HF-etched sample (Ti 3 C 2 T x -15 M).…”