甲酸在Pt-Sn(111)/C合金表面吸附的量子化学研究

采用周期平板模型, 结合密度泛函理论对HCOOH和CO在Pt-Sn(111)/C表面的top、brigde、hcp和fcc共计8个位点的吸附模型进行构型优化和能量计算, 并对吸附前后的频率、电荷、能带和态密度进行了研究. 计算结果表明fcc-Pt₃是较为有利的吸附位点, Sn掺杂之后费米能级右移, 导带增宽, 价带和导带的位置略微降低, 合金表面电子结构变化利于甲酸的吸附解离催化, 可使甲酸燃料电池阳极催化性能显著提高. 通过催化剂表面的抗中毒分析, 发现CO在Pt-Sn(111)/C表面的吸附能以两种趋势下降, 阳极催化剂掺杂改性后抗CO中毒能力增强.

Quantum Chemical Study on the Adsorption of Formic on a Pt-Sn(111)/CAlloy Surface

Density functional theory (DFT) and self-consistent periodic calculations were used to investigate the adsorption of formic acid (HCOOH) and carbon monoxide (CO) at eight sites, such as top, bridge, hcp and fcc, on a Pt-Sn(111)/C surface. The vibrational frequency, electric charge, energy band and density of states of HCOOH before and after adsorption on a Pt-Sn(111)/C surface were determined. The results show that before doping, the favored adsorption site for HCOOH and CO is the fcc-Pt3 site. After doping the surface with Sn, the Fermi level moves to the right, the conduction band broadens, and the valence and conduction bands lower slightly. The change of the electronic structure on Pt-Sn(111)/C promotes both the adsorption and dissociation of HCOOH, which can improve the performance of anode catalysts for direct formic acid fuel cells (DFAFCs). Based on the anti-poisoning analysis of the catalyst surface, it was also found that the adsorption energy of CO on Pt-Sn(111)/C surfaces is lower than that on Pt(111)/C ones. The results show that the adsorption energy of CO on Pt-Sn(111)/C decreases through two ways, and the anti-poisoning ability of the catalyst towards COis improved after doping with Sn.