Direct ethanol fuel cells (DEFCs) show a huge potential to power future electric vehicles and portable electronics, but their deployment is currently limited by the unavailability of proper electrocatalysis for the ethanol oxidation reaction (EOR). In this work, we engineer a new electrocatalyst by incorporating phosphorous into a palladium-tin alloy and demonstrate a significant performance improvement toward EOR. We first detail a synthetic method to produce Pd2Sn:P nanocrystals that incorporate 35% of phosphorus. These nanoparticles are supported on carbon black and tested for EOR. Pd2Sn:P/C catalysts exhibit mass current densities up to 5.03 A mgPd−1, well above those of Pd2Sn/C, PdP2/C and Pd/C reference catalysts. Furthermore, a twofold lower Tafel slope and a much longer durability are revealed for the Pd2Sn:P/C catalyst compared with Pd/C. The performance improvement is rationalized with the aid of density functional theory (DFT) calculations considering different phosphorous chemical environments. Depending on its oxidation state, surface phosphorus introduces sites with low energy OH− adsorption and/or strongly influences the electronic structure of palladium and tin to facilitate the oxidation of the acetyl to acetic acid, which is considered the EOR rate limiting step. DFT calculations also points out that the durability improvement of Pd2Sn:P/C catalyst is associated to the promotion of OH adsorption that accelerates the oxidation of intermediate poisoning COads, reactivating the catalyst surface.
This work was supported by the European Regional Development Funds and by the Spanish Ministerio de Economía y Competitividad through the project SEHTOP, ENE2016- 77798-C4-3-R, and ENE2017-85087-C3. X. Y. thanks the China Scholarship Council for the scholarship support. J. Liu acknowledges support from the Jiangsu University Foundation (4111510011). J. Li obtained International Postdoctoral Exchange Fellowship Program (Talent-Introduction program) in 2019 and is grateful for the project (2019M663468) funded by the China Postdoctoral Science Foundation. Authors acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and 2017 SGR 1246, and from IST Austria. ICN2 acknowledges the support from the Severo Ochoa Programme (MINECO, grant no. SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya. J. Llorca is a Serra Húnter Fellow and is grateful to MICINN/FEDER RTI2018-093996-B-C31, GC 2017 SGR 128 and to ICREA Academia program.
Yu X, Liu J, Li J, et al. Phosphorous incorporation in Pd2Sn alloys for electrocatalytic ethanol oxidation. Nano Energy. 2020;77(11). doi:10.1016/j.nanoen.2020.105116
Yu, X., Liu, J., Li, J., Luo, Z., Zuo, Y., Xing, C., … Cabot, A. (2020). Phosphorous incorporation in Pd2Sn alloys for electrocatalytic ethanol oxidation. Nano Energy. Elsevier. https://doi.org/10.1016/j.nanoen.2020.105116
Yu, Xiaoting, Junfeng Liu, Junshan Li, Zhishan Luo, Yong Zuo, Congcong Xing, Jordi Llorca, et al. “Phosphorous Incorporation in Pd2Sn Alloys for Electrocatalytic Ethanol Oxidation.” Nano Energy. Elsevier, 2020. https://doi.org/10.1016/j.nanoen.2020.105116.
X. Yu et al., “Phosphorous incorporation in Pd2Sn alloys for electrocatalytic ethanol oxidation,” Nano Energy, vol. 77, no. 11. Elsevier, 2020.
Yu X, Liu J, Li J, Luo Z, Zuo Y, Xing C, Llorca J, Nasiou D, Arbiol J, Pan K, Kleinhanns T, Xie Y, Cabot A. 2020. Phosphorous incorporation in Pd2Sn alloys for electrocatalytic ethanol oxidation. Nano Energy. 77(11), 105116.
Yu, Xiaoting, et al. “Phosphorous Incorporation in Pd2Sn Alloys for Electrocatalytic Ethanol Oxidation.” Nano Energy, vol. 77, no. 11, 105116, Elsevier, 2020, doi:10.1016/j.nanoen.2020.105116.