Monodispersed nickel phosphide nanocrystals (NCs) with different phases were successfully synthesized. The Ni5P4 NCs, with a solid structure, exhibited higher catalytic activity than the Ni12P5 and Ni2P NCs.
Nickel phosphide nanoparticles decorated on carbon nanotubes were synthesized by in situ thermal decomposition for the first time. The Ni2P/CNT nanohybrid exhibits high activity and stability for hydrogen evolution.
As a new, emerging class in catalysis field, single-atomic-site catalysts (SASCs) have displayed outstanding activities, selectivities, and stabilities in a range of important catalytic reactions. The compositions and structures of SASCs have a great impact on catalytic performances; therefore, the central task is to rationally manipulate the structures with atomic-level precision, and thereupon to design different active sites to promote the overall performances.Here, we compare SASCs with clusters/nanoparticles in term of their catalytic behaviors, and systematically interpret the impacts of the microscopic structures of SASCs on catalytic performances. Subsequently, we summarize the reports on synergistic catalysis over diatomic, multiatomic sites, single-atom alloys, and atomic interfaces, and highlight the great significance of in situ characterization technologies for monitoring the active sites. Finally, we discuss the limitations, development trends, and future challenges of SASCs, and present an outlook on further constructing more sophisticated active sites for more complex catalytic reactions.
ADVANTAGES OF SINGLE-ATOMIC SITE CATALYSISComparison between Single-Atomic-Site Catalysts and Cluster/Nanoparticle Catalysts Conventional heterogeneous catalysts typically include cluster catalysts and nanoparticle (NP) catalysts, which, compared with their homogeneous counterparts,
The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M-Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M-Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M-Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe-Co2P/NCNTs > Ni-Co2P/NCNTs > Cu-Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the  crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Fe(δ+) has the highest positive charge among all the M-Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe-Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER.
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