Bionic Preparation of CeO2-Encapsulated Nitrogen Self-Doped Biochars for Highly Efficient Oxygen Reduction
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2020-01-02 |
| Journal | ACS Applied Materials & Interfaces |
| Authors | Pi Liu, Rui Jiang, Wanxin Cai, Lei Wang, Yangyang Wang |
| Institutions | Chinese Research Academy of Environmental Sciences, Wuhan University |
| Citations | 48 |
Abstract
Section titled āAbstractāThis study reports the superior performance of novel carbonaceous materials, CeO<sub>2</sub>-encapsulated nitrogen-doped biochars [BC-Ce-<i>X</i> (<i>X</i> = 1 and 2)], for oxygen reduction reaction (ORR). The biomass precursor of this value-added biochar material was biomimetically prepared via a hydroponic operation in the Ce-enriched solution. The characterization results showed that CeO<sub>2</sub> with large amounts of oxygen vacancies was stably embedded in the N self-doped biochars during the pyrolytic processes. The measured specific surface areas of cerium-free biochar (BC sample), BC-Ce-1, and BC-Ce-2 were 79, 566, and 518 m<sup>2</sup>/g, respectively. The BC-Ce-<i>X</i> (<i>X</i> = 1 and 2) showed excellent ORR performances with onset potentials of ā¼0.90-0.91 V, which outperformed the commercial 10 wt % Pt/C and BC. Compared with Pt/C, the BC-Ce-2 had better methanol tolerance and stability. Also, BC-Ce-2 displayed excellent electrochemical activity for Zn/air batteries. Controlled experiments and density functional theoretical calculations illustrated the synergistic effect between the pyri-N/C centers and CeO<sub>2</sub> with oxygen vacancies in ORR. The Lewis base sites, created by pyri-N and oxygen vacancies, greatly facilitated the chemisorption of O<sub>2</sub> molecules.