Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through water decomposition are feasible methods to produce green and clean energy. Herein, we report a facile two-step strategy for the preparation of non-noble metal defect-rich nanosheets by an electrochemical process at room temperature. First-principle calculations are used to study the bifunctional catalytic reaction mechanism of defect engineering in transition-metal dichalcogenides (TMDs); from the first-principle calculations, we predicted that the rich S vacancies on the nanosheet promoted electron transfer and reduced the energy barrier of electrocatalysis. As a substantiation, we conducted HER/ OER electrochemical characterizations and found that the defectrich atomic-thick tantalum sulfide is a kind of dual-function electrocatalyst with enhanced comprehensive properties of Tafel slope (39 mV/dec for HER, 38 mV/dec for OER) and low overpotential (0.099 V for HER, 0.153 V for OER) in acidic and alkaline environments, respectively. Likewise, the defect-rich catalysts exhibit high stability in acidic and alkaline solutions, which have potential applications as electrocatalysts for the large-scale production of hydrogen and oxygen.
Perovskite
single crystals have emerged as attractive structures
for integrated devices. However, due to uncontrolled crystallization,
the versatile and scalable fabrication of arrays of perovskite single
crystals with controllable morphology and location remains a great
challenge. Here, we report a facile printing strategy to controllably
fabricate perovskite single-crystal arrays with well-defined morphology
and location. Through modulating perovskite precursor ion aggregation
in microdroplets by controlling the temperature of substrates, perovskite
single-crystal arrays with controlled morphologies are fabricated,
which can be selectively integrated on silicon for high-performance-type
tailored laser arrays. More importantly, integrated perovskite single-crystal
microstructures are printed, showing an efficiently coupling property
with well-maintained intrinsic characters of the original signals.
This strategy enables fully inkjet-printed morphology-controllable
perovskite single-crystal arrays and functional coupling-structure
arrays, which offers new opportunities for integrated photonic and
optoelectronic devices.
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