Enhanced hydrogen evolution reaction in alkaline solution by constructing strong metal-support interaction on Pd-CeO2-x-NC hybrids

Diminishing the size of metal nanostructures can significantly improve the performance of catalysts. However, the self-aggregation of small particles is still an insurmountable obstacle, resulting in the unfavorable stability and recyclability. Herein, we designed and fabricated the Pd-CeO2-x-NC catalyst though an accurate deposition strategy to downsize the Pd particle to sub-nanometer level and enhance its running stability. The CeO2-x nanoclusters were firstly dispersed on the nitrogen-doped carbon nanosheets. Further, the active Pd sub-nanoclusters were accurately scattered on the surface of CeO2-x ascribing to the strong metal-support interaction (SMSI) between Pd and CeO2-x, which was beneficial to promote the catalytic activity. Subsequently, the high oxidation state Pdn+ species were formed due to the electron transfer from Pd to CeO2-x caused by the SMSI effect. Strikingly, the HER performance of Pd-CeO2-x-NC was surprisingly correlated with the ratio of Pdn+, suggesting Pdn+ acted as the dominant active species. Besides, the SMSI effect stabilized the valence state of active Pdn+ species and prevented the sub-nanometer Pd clusters from aggregation, which played a vital role for the enhanced stability of the hybrid catalyst. This synthetic process described here is contributed to prepare various nanostructured catalysts with satisfactory stability through the direct targeting strategy.