It is a challenge to improve the long-term durability of Pd-based electrocatalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, Pd/CeO2-C-T (T=800, 900 and 1000℃) hybrid catalysts with metal-support interaction are prepared from Ce-based metal organic framework (Ce-MOF) precursor. Abundant tiny CeO2 nanoclusters are produced to form nanorod structures with uniformly distributed carbon through a calcination process. Meanwhile, both carbon and CeO2 nanoclusters have good contact with the following deposited surfactant-free Pd nanoclusters. Benefited from the large specific surface area, good conductivity and structure integrity, Pd/CeO2-C-900 exhibits the best electrocatalytic ORR performance: onset potential of 0.968 V and half-wave potential of 0.857 V, outperforming those obtained on Pd/C counterpart. In addition, the half-wave potential only shifts 7 mV after 6000 cycles of accelerated durability testing, demonstrating robust durability.
Zhenxing Wang,Hongli Zhao,Kaicha Chen,Fangfang Zhou,Shlomo Magdassi,Minbo Lan
Two-dimensional (2D) porous carbon-based composite nanosheets loaded with metal oxide nanoclusters are expected to be promising electrocatalysts for high-performance electrochemical sensors . However, for this complicated composite material, strict reaction conditions and complex synthesis steps limit its general application in electrochemical detection . Here we present a facile method to fabricate 2D mesoporous nitrogen-rich carbon nanosheets loaded with CeO 2 nanoclusters (2D-mNC@CeO 2 ), for fabricating superoxide anions (O 2 •− ) electrochemical sensor. The method is based on block copolymers self-assembly and the affinity of polydopamine to metal ions to obtain organic-inorganic hybrid, which can be directly converted into 2D-mNC@CeO 2 through carbonization strategy without structural deterioration . Characterizations demonstrate that the 2D-mNC@CeO 2 owned the 2D N-doped carbon structure with an interlinked hierarchical mesoporous and the uniformly dispersed CeO 2 nanoclusters on the surface. Benefitted from the unique structure, the 2D-mNC@CeO 2 shortens electron transfer distance, enhances mass transfer efficiency, exposes numerous active sites, and obtain a high Ce 3+ /Ce 4+ ratio for improving electrocatalytic performance. The 2D-mNC@CeO 2 /SPCEs sensors for O 2 •− detection has a detection limit of 0.179 μM (S/N = 3) and sensitivity of 401.4 μA cm -2 mM -1 . The sensors can be applied to capture electrochemical signals of O 2 •− released from HepG2 cells, demonstrating the application potential of the sensors to monitor O 2 •− in biological fields.
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