Development of noble-metal single atomic site catalysts with high metal loading is highly required for many important chemical reactions but proves to be very challenging. Herein, we report a Na2CO3 salt-assisted one-pot pyrolysis strategy from EDTA–Pt complex to N-doped graphene with isolated Pt single atomic sites (Pt-ISA/NG) with Pt loading up to 5.3 wt %. The X-ray absorption fine structure analysis and spherical aberration-correction electron microscopy demonstrate an atomic dispersion of single Pt species on graphene support and stabilized by nitrogen in Pt–N4 structure. The Pt-ISA/NG catalyst exhibits high catalytic activity and reusability for anti-Markovnikov hydrosilylation of various terminal alkenes with industrially relevant tertiary silanes under mild conditions. In hydrosilylation of 1-octene, the Pt-ISA/NG catalyst delivers an overall turnover frequency of 180 h–1, which is a 4-fold enhancement compared with commercial Pt/C.
Metal-organic frameworks (MOF) have recently emerged as versatile precursors to fabricate functional MOF derivatives for oxygen evolution reactions (OER). Herein, we developed a controlled partial pyrolysis strategy to construct robust NiCo/Fe3O4 heteroparticles within MOF-74 for efficient OER using trimetallic NiCoFe-MOF-74 as precursor. The partial pyrolysis method preserves the framework structure of MOF for effective substrates diffusion while producing highly active nanoparticles. The as-prepared NiCo/Fe3O4/MOF-74 delivered remarkably stable OER current with an overpotential as low as 238 mV at 10.0 mA cm-2 and an Tafel slop of 29 mV/dec, outperforming those of pristine NiCoFe-MOF-74, totally decomposed MOF derivatives, and most reported non-noble metal based electrocatalysts. The key for the formation of NiCo/Fe3O4/MOF-74 nanostructures is that the metals can be decomposed from NiCoFe-MOF-74 in the order of Ni, Co, and Fe under controlled heat treatment. Density functional theory calculations reveals that the underlying NiCo promotes the OER activity of Fe3O4 through exchange stabilization of active oxygen species.
Developing a noble-metal-free robust and effective electrocatalyst with enhanced active sites for overall water splitting is of great significance yet challenging.
In the research and development of noble-metal free catalysts, copper-based materials such as copper selenite have shown interest as electrocatalysts to drive the oxygen evolution reaction (OER) in basic medium, however their Hydrogen evolution reaction (HER) activity is still unexplored. Therefore, we have performed the synthesis of cobalt doped copper selenite nanoparticles which can robustly and effectively do electrocatalysis for both the OER and HER in basic medium electrolyte. The novelty lies in the fact that microwave synthesis procedure utilizing oxidizing agent as a key precursor is entirely new, this particular material was never employed in water splitting and catalyst need very low amount of binder. The results revealed that cobalt doped copper selenite have a relatively lower starting potential and a higher current density due to the synergistic effects of a large active area, quick charge, mass transport, and a three-dimensional conducting path, having OER and HER overpotentials of 365 mV and 226mV at 10 mA/cm2 current densities, respectively. We found a novel doped structure featuring porous surfaces and distinctive rice like morphology which facilitate an efficient electron transportation during the water splitting thereby illustrating an exceptional performance of this system along with rapid synthesis and lower costs.
Copper sulfides are broadly explored as the possible cathode materials for rechargeable magnesium batteries on account of their high theoretical capacity of 560 mAh g-1. However, the CuS cathodes usually suffer from serious capacity decay caused by structure collapse during the repeated magnesiation/demagnesiation process. Herein, we present a cuprous self-doping strategy to synthesize mesoporous CuS nanotubes with robust structural stability for rechargeable magnesium batteries and regulate their electrochemical magnesium storage behavior. Electrochemical results show that the mesoporous CuS nanotubes can exhibit high specific capacity, remarkable cycling performance, and good rate capability. The observed discharge capacity of the mesoporous CuS nanotubes could reach about 281.2 mAh g-1 at 20 mA g-1 and 168.9 mAh g-1 at 500 mA g-1. Furthermore, a remarkable ultralong-term cyclic stability with a reversible capacity of 72.5 mAh g-1 at 1 A g-1 is obtained after 550 cycles. These results demonstrate that the mesoporous nanotube structure and the simple cuprous self-doping effect could promote the practical application of copper sulfide cathode materials for rechargeable magnesium batteries.
Prolonging the cycle life of silicon-based materials at large current is particularly meaningful for the achievement of advanced high-power lithium ion batteries.
Abstract Graphene‐based materials are considered as one of the promising photocatalysts for hydrogen production from solar‐driven water splitting yet subject to zero bandgap limitation. Here, we report an efficient one‐step pyrolysis for preparing p‐type boron‐doped monolayer graphene. Through varying the dopant content, the bandgap of the boron‐doped graphene can be tuned. Moreover, a p‐type conductivity behavior of the boron‐doped monolayer graphene is demonstrated by the four‐probe measurement and Hall effect measurement. The boron‐doped graphene can service as an efficient semiconductor photocatalyst for hydrogen production from water splitting under visible‐light irradiation. The optimized boron‐doped graphene can deliver a high H 2 production rate of 219.3 μmol h −1 g −1 without any cocatalyst. The photocatalyst can be recycled at least four times without obvious activity decay and maintain high H 2 production rate of 215.3 μmol h −1 g −1 after 60 h reaction, indicative of excellent stability. This work may open up a new avenue for fabrication of new photocatalysts based on p‐type boron‐doped monolayer graphene.
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