Reducing the particle sizes of transition metals (TMs) and avoiding their aggregation are crucial for increasing the TMs atom utilization and enhancing their industrial potential. However, it is still challenging to achieve uniform distributed and density‐controlled TMs nanoclusters (NCs) under high temperatures due to the strong interatomic metallic bonds and high surface energy of NCs. Herein, a series of TMs NCs with controllable density and nitrogen‐modulated surface are prepared with the assistance of a selected covalent organic polymer (COP), which can provide continuous anchoring sites and size‐limited skeletons. The prepared Ir NCs show superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities than commercial Pt/C and Ir/C in both acid and alkaline media. In particular, the as‐prepared Ir NCs exhibit remarkable full water splitting performance, reaching a current density of 10 mA cm−2 at ultralow overpotentials of 1.42 and 1.43 V in alkaline and acidic electrolyte, respectively. The excellent electrocatalytic activities are attributed to the increased surface atom utilization and the improved intrinsic activity of Ir NCs. More importantly, the Ir NCs catalyst shows superior long‐term stability due to the strong interaction between Ir NCs and the N‐doped carbon layer.
In this study, we demonstrate noble metal-free Fe–N-codoped
graphene nanoshells (Fe–N/GNS) derived from petroleum pitch
as highly efficient and cost-effective catalysts for nitroaromatics
reduction. By employing α-Fe2O3 nanoparticles
simultaneously as both the hard template and the metal source, Fe–N/GNS
can be facilely synthesized through the template-oriented method,
followed by thermal annealing with urea for nitrogen doping. Owing
to the high-dispersed synergetic Fe–N active sites as well
as the hierarchical porous nanoshell structure, the Fe–N/GNS
catalysts show remarkable catalytic performance and good tolerance
for the reduction of nitroaromatics with NaBH4 aqueous
solution. The optimized Fe–N/GNS-800 corresponds to pseudo-first-order
kinetics for p-nitrophenol reduction at room temperature,
with the rate constant (k) reaching 1.23 min–1. The reinforced structure also allows the catalyst
to be readily recycled a dozen times without activity deterioration.
This work may provide a new avenue to facilely fabricate cost-effective
but powerful catalysts for nitroaromatics reduction and beyond.
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