Enhancing C–C Bond Scission for Efficient Ethanol Oxidation using PtIr Nanocube Electrocatalysts

Abstract

Ethanol is a green, sustainable, and high-energy-density liquid fuel that holds great promise for direct liquid fuel cells (DLFCs). However, it remains highly challenging to develop electrocatalysts that selectively promote the C–C bond scission for the ethanol oxidation reaction (EOR). Here, we report the facile synthesis of PtIr alloy core–shell nanocubes (NCs) with Ir-rich shells as effective EOR electrocatalysts. We find that (100)-exposed Pt38Ir NCs with one-atom-thick Ir-rich skin exhibit unprecedented EOR activity, high CO2 selectivity, and long-term stability, while pure Pt NCs and Pt17Ir NCs (two-atom thick Ir-rich skin) show less activity and lower CO2 selectivity. We demonstrate that the Pt38Ir NCs electrocatalyst can deliver a current density up to 4.5 times higher than that of Pt/C with a lower EOR onset potential by 320 mV. Its CO2 current density at 0.85 V is 14 times higher than that of commercial Pt/C. We show that the enhanced EOR activity is mainly due to the Ir-rich PtIr(100) facet that not only favors the splitting of the C–C bond by strongly adsorbing the *C x H y O/C x H y species but also promotes the desorption of CO from the PtIr surface. This work highlights the critical role of surface atom layers on shape-engineered catalysts and demonstrates a strategy for the design of efficient EOR electrocatalysts.

Recent Advances in Plasmonic Nanostructures for Enhanced Photocatalysis and Electrocatalysis

“…AOR (e.g., methanol oxidation reaction, MOR and ethanol oxidation reaction, EOR) is the essential process for direct alcohol fuel cells. [ 180–184 ] Pt‐ and Pd‐based materials are the present benchmark catalysts for AOR. In the past few years, some examples of plasmon‐enhanced AOR have been reported but the mechanism remains controversial.…”

On the oxidation mechanism of C1-C2 organic molecules on platinum. A comparative analysis

“…Thus, the Pt(110) electrode displays the highest activity for the C-C bond splitting, whereas this step is very unfavorable on Pt(111) electrodes, producing mostly acetic acid during the reaction [4]. DFT calculations demonstrated that the reason of the poor ability of Pt(111) to oxidize ethanol to CO2 is related with its higher activation barrier for C-C bond breaking (1.36 eV) when compared to Pt(100) (0.65 eV) and that the bond cleavage occurs through strongly chemisorbed precursors, such as CH2CO or CHCO, only at low-coordinated surface sites [43] or (110) steps on (111) terraces [41], corroborating the experimental results [44].…”

“…FTIR experiments showed an increase of the CO and CO2 bands by the modification of Pt basal planes with low coverage of Os, which suggest a better capability of the Pt-Os system to cleave the C-C bond of ethanol, in comparison with the non-modified platinum electrodes. On the other hand, other metals such as Rh and Ir have been explored as secondary metals in Pt-based nanoparticles for EOR [43,50].…”

A Tensile‐Strained Pt–Rh Single‐Atom Alloy Remarkably Boosts Ethanol Oxidation

“…[10][11][12][13][14][15] Combining these approaches in a rational manner would be a promising way to substantially improve the EOR, yet the underlying knowledge about their contributions is largely lacking. [10][11][12][13][14][15][16][17][18] Therefore, it is highly desirable to employ tailored nanostructures to resolve these important issues and contribute to the practical deployment of DEFCs by identifying versatile EOR electrocatalysts possessing high atom utilization of noble metals, high mass-normalized activity at low overpotentials, high C1-pathway selectivity, long-term durability, and superior anti-poisoning ability. [1] To maximize atom utilization, single-atom catalysts (SACs) have emerged as one of the most promising frontiers in materials chemistry.…”