Tao Chen,Manli Wang,Donghang Hu,Qianlin Ju,Kaige Zhao,Liang Fu,Zelin Chen,Xiaolong Yu,Changjiu Li
The mainstream electrocatalysts for direct ethanol fuel cells (DEFCs) are Pt- or Pd-based nanomaterials, which are severely hampered by CO intermediate poisoning and the relatively low selectivity of the C1 pathway in anodic ethanol oxidation reaction (EOR), thereby impeding the efficiency enhancement and practical application of DEFCs. Herein, we report a Pt-decorated amorphous PdS nanowire [denoted as a-Pd(S)NWs/Pt] catalyst with abundant crystalline/amorphous heterogeneous interfacial active sites for alkaline EOR. The a-Pd(S)NWs/Pt was demonstrated a superior EOR mass activity of 6.16 A·mgPd+Pt–1, which is 22.81 times over that of commercial Pt/C (0.27 A·mgPt–1) and 34.22 times over that of commercial Pd/C (0.18 A·mgPd–1). Additionally, the a-Pd(S)NWs/Pt exhibited considerable stability, significantly enhanced resistance to CO poisoning and enhanced selectivity for the EOR C1 pathway. Density functional theory calculations and experimental results further revealed that the optimized COads and OHads binding energies due to the decoration of Pt nanoclusters can be responsible for the enhanced CO resistance and C1 selectivity of a-Pd(S)NWs/Pt. Furthermore, benefiting from its optimized electronic configuration at the interfacial active sites and the appropriate intermediate adsorption capacity, the a-Pd(S)NWs/Pt electrocatalyst was successfully extended to the electrocatalytic methanol and ethylene glycol oxidation reaction systems.
As a novel electrochemical energy conversion device, direct ethanol fuel cells are currently encountering two significant challenges: CO poisoning and the difficulty of C–C bond cleavage in ethanol. In this work, an amorphous PdS nanowires/ultrafine IrMnOx bimetallic oxides (denoted as a-PdS/IrMnOx NWs) catalyst with abundant oxide/metal (crystalline/amorphous) inverse heterogeneous interfaces was synthesized via a hydrothermal process succeeded by a nonthermal air-plasma treatment. This unique interfacial electronic structure along with the incorporation of oxyphilic metal has resulted in a significant enhancement in the electrocatalytic performance of a-PdS/IrMnOx NWs toward the ethanol oxidation reaction, achieving current densities of 12.45 mA·cm–2 and 3.68 A·mgPd–1. Moreover, the C1 pathway selectivity for ethanol oxidation has been elevated to 47%, exceeding that of other as-prepared Pd-based counterparts and commercial Pd/C catalysts. Density functional theory calculations have validated the findings that the decoration of IrMn species onto the amorphous PdS surface has induced a charge redistribution in the interface region. The redistribution of surface charges on the a-PdS/IrMnOx NWs catalyst results in a significant decrease in the activation energy required for C–C bond cleavage and a notable weakening of the CO binding strength at the Pd active sites. Consequently, it enhanced both the EOR C1 pathway selectivity and CO poisoning resistance to the a-PdS/IrMnOx NWs catalyst.
Jianpo Chen,Xiaohong Tan,Weidong He,Yingying Guo,Yuhang Xiao,Hao Cui,Chengxin Wang
Efficient ethanol oxidation reaction (EOR) catalysts with anti-poisoning ability and high selectivity are in high demand for the widespread application of direct ethanol fuel cells (DEFCs). Here, the PdSnW ternary alloy nanoparticles are synthesized by a facile solvothermal method and exhibit an enhanced EOR catalytic performance. CO stripping experiment, X-ray photoelectron spectroscopy and in situ Fourier transform infrared are employed to study the correlation between catalyst structure and EOR catalytic performance. The oxyphilic Sn and W not only provide dangling O-H bond, accelerating the subsequent oxidation of adsorbed intermediate CO species, but also moderate the electron state of Pd, enhancing the adsorption of CH3CH2OH, thus resulting in the promotion of C-C bond cleavage and an increased C1 selectivity. As a consequence, PdSnW alloy nanoparticle catalyst exhibit a better stability and a higher mass activity than those of Pd/C, PdSn and PdW, respectively. This work not only offers novel insights to strategically design highly efficient electrocatalysts for ethanol oxidation, but also further clarifies the inherent structure-activity relationship.
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