Acta Chim. Sinica ›› 2017, Vol. 75 ›› Issue (2): 189-192.

Special Issue: 先进电池材料

Communication

### 锗纳米管催化的氧还原反应:催化性能和机理研究

1. a 北京大学工学院 先进电池材料理论与技术北京市重点实验室 北京 100871;
b 西南石油大学化学化工学院 新能源材料与技术研究中心 成都 610500
• 投稿日期:2016-08-29 修回日期:2016-10-09 发布日期:2016-10-10
• 通讯作者: 夏定国,E-mail:dgxia@pku.edu.cn;Tel.:010-62767962;Fax:010-62767962 E-mail:dgxia@pku.edu.cn
• 基金资助:

项目受国家自然科学基金（Nos.51602270，51671004）资助.

### Germanium Nanotube as the Catalyst for Oxygen Reduction Reaction: Performance and Mechanism

Chen Xina,b, Yan Huijuna, Xia Dingguoa

1. a Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials, College of Engineering, Peking University, Beijing 100871;
b The Center of New Energy Materials and Technology, College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500
• Received:2016-08-29 Revised:2016-10-09 Published:2016-10-10
• Contact: 10.6023/A16080451 E-mail:dgxia@pku.edu.cn
• Supported by:

Project supported by the National Natural Science Foundation of China (Nos. 51602270, 51671004).

One of the major technical barriers to the commercialization of proton exchange membrane fuel cells is the high cost of Pt-based oxygen reduction reaction (ORR) electrocatalysts. In this paper, the ORR catalytic performance and the possible mechanism on (5,5) germanium nanotube (GeNT) were studied by density functional theory methods using DZP basis set. The results indicate that the ORR on the GeNT may undergo three mechanisms including O2 dissociation, OOH dissociation and H2O2 dissociation. For any of the above mechanism, the whole process could easily take place on the GeNT with a complete 4e- ORR pathway. The adsorption properties of the ORR intermediates, especially for O and OH, are also very important for evaluating the catalytic performance. The calculated adsorption energies of the above species are -4.33 and -2.21 eV respectively, much close to those on the Pt. Furthermore, the adsorption energy of H2O on the GeNT is only -0.05 eV, much weaker than the O2 binding, indicating the catalytic cycle of ORR could repeat most easily on the GeNT. Therefore, both the reaction energies of the ORR steps and the adsorption energies of ORR intermediates show that the current GeNT model has the catalytic performance similar to that of precious Pt catalyst. Furthermore, the solvent effect was also studied by using three-water-molecule clusters as the real solvent. The obtained results indicate that the solvent effect could affect the geometrical structure of some adsorbed ORR intermediates, such as atomic O. This would lead to the decrease of the heat loss during the O2 dissociation mechanism. The decreased heat loss would accelerate the following electron transfer steps, due to the fact that an effective electrocatalyst must make the energy loss as small as possible for non-electron-transfer step, in which case the cathode electrocatalyst would deliver all the Gibbs energy of the ORR as electrical work. With solvation, the heat loss is slightly increased from *O2 to *OOH, and decreased from *OOH to *OH in the H2O2 dissociation mechanism, which are also more favorable for ORR.