The development of
low-cost and high-performance electrocatalysts
for simultaneously boosting the hydrogen evolution reaction (HER),
oxygen evolution reaction (OER), and oxygen reduction reaction (ORR)
is highly crucial but still challenging. Herein, a facile one-step
solid-phase polymerization and confined pyrolysis strategy is developed
for scalable synthesis of a Fe
x
P/Fe
3
C-based (
x
= 1, 2) heterojunction with controllable
iron phosphide crystal phases. By effective heterojunction interface
regulation, the strong synergic effect between FeP/Fe
3
C
and N- and P-codoped carbon (NPC) modified the electronic structure,
resulting in an excellent electrocatalytic performance for the HER,
OER, and ORR synchronously. Typically, the FeP/Fe
3
C@NPC
catalyst exhibits efficient HER activity with a low overpotential
of 10 mA cm
–2
for the HER (97 mV) and OER (440 mV)
and a high half-wave potential of 0.87 V for the ORR, as well as excellent
stability in alkaline media. Theoretical calculations demonstrated
that Fe
3
C can promote the activation of water molecules,
while FeP is beneficial to the removal of H
2
and the FeP/Fe
3
C heterojunction can facilitate both Volmer and Heyrovsky
steps in the HER process simultaneously. Moreover, FeP has a stronger
inhibitory effect on OH adsorption, revealing that the FeP/Fe
3
C heterojunction also shows a better promoting effect for
both the OER and ORR, respectively.
Titanium silica (TS-1) membrane catalysts grown on the surfaces of spherical substrates can both exploit the high catalytic performance and facilitate their separation from products after the reaction. In this work, a simple static crystallization method was used to perform the in situ construction of a TS-1 membrane on the surfaces of micron-sized spherical carriers. The shortcomings of the TS-1 membrane under static crystallization conditions were overcome by in situ dynamic crystallization, and the effect of rotation speed on the formation of the molecular sieve membrane was investigated. The results showed that the molecular sieve membrane was smooth and homogeneous, with a higher synthesis efficiency at a slow rotational speed. The micron TS-1 spherical membrane catalytic chloropropene epoxidation reaction was investigated in a fixed bed, and the conversion of hydrogen peroxide and selectivity of epichlorohydrin reached 99.4 and 96.8%, respectively. After being reused twice, the catalyst still maintained a stable catalytic performance.
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