Shuqiang Wang,Yanpeng Xue,Feifei Huang,Zhigang Yu,Ying Jin
Fine-tuning the surface structure of transition metal oxides at the atomic level is a promising way to improve the catalytic properties of materials . However, the influence of crystal surface structure on electrode reaction kinetics is still limited. In this study, we propose an in-situ synthesis strategy to obtain two-dimensional carbon/cerium oxide core–shell nanosheets by thermal decomposition of Ce-MOF nanosheets grown on the surface of carbon nanostructures , and fine-tuning the surface structure by introducing oxygen vacancies through defect engineering during the oxide nucleation process is conducted to obtain controllable exposed {1 1 1} and {1 1 0} surface CeO 2 @C composites. Both experiments and theoretical calculations show that the {1 1 0} -dominated nanocomplex (CeO 2 @C-350S) has better kinetic behavior and catalytic activity due to its abundant surface defects , which is manifested in higher active surface area , richer carrier concentration, and better promotion of diffusion and adsorption. In addition, CeO 2 @C-350S electrode has an extremely wide linear range and good stability in the electrochemical detection of nitrite. After 1000 times of the accelerated cycle experiments, CeO 2 @C-350S electrode still maintains 79.3 % of its initial current response, and recovers to 87.3 % after 10 min of stopping the test. The electrode stability is excellent, which is attributed to the clever carbon shell structure of the material. This synthesis strategy can be extended to other carbon-based oxide composite catalysts to improve the electrocatalytic performance and overall stability by adjusting the surface structure.
The development of direct methanol fuel cells (DMFCs) is partially limited by the poor kinetics of methanol oxidation reaction (MOR) at the anode side. It was reported that the interaction between Pt and CeO 2 enhances the electrocatalytic performance of Pt catalyst for MOR. In this work, a hybrid material (CeO 2 –C) composed of CeO 2 and carbon was successfully prepared by a simple hydrothermal method followed by calcination in inert atmosphere . The hierarchically porous nanostructure and especially good electronic conductivity of CeO 2 –C make it an excellent support for Pt particles for application in electrocatalytic process. TEM investigation reveals that triple-phase interface of Pt, carbon and CeO 2 forms in Pt/CeO 2 –C catalyst. Performance of the as-prepared catalyst for MOR was studied in alkaline medium. The Pt/CeO 2 –C catalyst shows superior catalytic performance for MOR compared with Pt/CeO 2 and the physical mixture of Pt/CeO 2 and acetylene black (Pt/CeO 2 +C). The significantly improved performance can be attributed to the synergetic effect between Pt particles and CeO 2 –C support, and the better conductivity of CeO 2 –C. This study provides a possible method to expand the application potential of CeO 2 materials in MOR, and may also be used in other electrocatalytic process.
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