Identification
of active sites for highly efficient catalysts at
the atomic scale for water splitting is still a great challenge. Herein,
we fabricate ultrathin nickel-incorporated cobalt phosphide porous
nanosheets (Ni-CoP) featuring an atomic heterometallic site (NiCo16–x
P6) via a boron-assisted
method. The presence of boron induces a release-and-oxidation mechanism,
resulting in the gradual exfoliation of hydroxide nanosheets. After
a subsequent phosphorization process, the resultant Ni-CoP nanosheets
are implanted with unsaturated atomic heterometallic NiCo16–x
P6 sites (with Co vacancies) for alkaline
hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).
The optimized Ni-CoP exhibits a low overpotential of 88 and 290 mV
at 10 mA cm–2 for alkaline HER and OER, respectively.
This can be attributed to reduced free energy barriers, owing to the
direct influence of center Ni atoms to the adjacent Co/P atoms in
NiCo16–x
P6 sites. These
provide fundamental insights on the correlation between atomic structures
and catalytic activity.
The oxygen reduction reaction (ORR) on transition single-atom catalysts (SACs) is sustainable in energyconversion devices. However, the atomically controllable fabrication of single-atom sites and the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct OÀ O cleavage pathway through using a bi-functional ligand-assisted strategy to pre-control the distance of hetero-metal atoms. Concretely, the as-synthesized FeÀ Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half-wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the FeÀ Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero-diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.
Developing efficient and robust catalysts to replace Pt group metals for oxygen reduction reaction (ORR) is conducive to achieve highly efficient energy conversion. Here, we develop a general ion exchange...
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