Rongcheng Peng,Yang Gao,Hussein A. Younus,Yan Zhang,Wenpeng Ni,Shiguo Zhang
Upgrading CO2 to formate systems is a promising avenue for fuel production, and SnOx is a unique low-cost candidate for this conversion. However, the high oxygen affinity of Sn sites leads to a strong adsorption of O-bound intermediates, resulting in a low efficiency of CO2 reduction. Herein, density functional theory (DFT) calculations confirmed that a H-doping strategy of SnO2 produces partially depleted positive charge Sn sites, weakening the adsorption of HCOO* and boosting the electron transfer kinetics. Experimentally, H-doped commercial SnO2 nanoparticles (H-SnO2) indeed had enhanced intrinsic activity for CO2-to-formate conversion with suppressed hydrogen evolution performance. Remarkably, H-SnO2 achieves over 90.0% formate selectivity within −0.6 to −1.0 V (vs RHE) at the industrial current density of 220 mA cm–2. Electrochemical measurements and in situ Raman spectra analysis together disclosed that H-doping speeds up the kinetic rate for the first electron transfer of CO2 reduction and also promotes formate desorption, resulting in the impressively high current density and selectivity of H-SnO2.
Chaoyi Yang,Guangqin Wang,Jianchao Yue,Zihao Dai,Wei Luo
The development of active and anti-CO-poisoning Pt-based electrocatalysts toward an alkaline hydrogen oxidation reaction (HOR) is highly desirable for the practical application of anion exchange membrane fuel cells. Herein, we report the synthesis of intermetallic Pt alloys with introduction of oxophilic Sn (including Pt3Sn and PtSn), significantly boosting the alkaline HOR performance and CO tolerance. Experimental results including in situ surface-enhanced infrared absorption spectroscopy and theoretical calculations unravel that the d band centers of Pt in Pt3Sn and PtSn are notably down shift due to the introduction of oxophilic Sn, thereby leading to the decreased adsorption energy of both hydrogen and CO, which together with the enhanced adsorption energy of OH species on Sn sites contribute the lowered energy barrier for water formation and CO oxidation. As expected, the obtained Pt3Sn and PtSn both present improved HOR performance and anti-CO-poisoning ability. Specially, Pt3Sn depicts three times specific activity and four times mass activity higher than that of Pt, while PtSn maintains over 90% HOR activity after the CO poisoning.
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