The modulation of the electronic structure is the effective
access
to achieve highly active electrocatalysts for the hydrogen evolution
reaction (HER). Transition-metal phosphide-based heterostructures
are very promising in enhancing HER performance but the facile fabrication
and an in-depth study of the catalytic mechanisms still remain a challenge.
In this work, the catalytically inactive n-type CeO
x
is successfully combined with p-type CoP to form the CoP/CeO
x
heterojunction. The crystalline–amorphous
CoP/CeO
x
heterojunction is fabricated
by the phosphorization of predesigned Co(OH)2/CeO
x
via the as-developed reduction–hydrolysis
strategy. The p–n CoP/CeO
x
heterojunction
with a strong built-in potential of 1.38 V enables the regulation
of the electronic structure of active CoP within the space–charge
region to enhance its intrinsic activity and facilitate the electron
transfer. The functional CeO
x
entity and
the negatively charged CoP can promote the water dissociation and
optimize H adsorption, synergistically boosting the electrocatalytic
HER output. As expected, the heterostructured CoP/CeO
x
-20:1 with the optimal ratio of Co/Ce shows significantly
improved HER activity and favorable kinetics (overpotential of 118
mV at a current density of 10 mA cm–2 and Tafel
slope of 77.26 mV dec–1). The present study may
provide new insight into the integration of crystalline and amorphous
entities into the p–n heterojunction as a highly efficient
electrocatalyst for energy storage and conversion.
An amorphous NiCoFeCrMo-based high-entropy hydroxide possesses the maximum content of high-valence Ni3+ species, boosting the oxygen evolution electrocatalytic performance.
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