In Situ Photosynthesis of an MAPbI₃/CoP Hybrid Heterojunction for Efficient Photocatalytic Hydrogen Evolution

Abstract

Halide perovskite like methylammonium lead iodide perovskite (MAPbI3) with its prominent optoelectronic properties has triggered substantial concerns in photocatalytic H2 evolution. In this work, to attain preferable photocatalytic performance, a MAPbI3/cobalt phosphide (CoP) hybrid heterojunction is constructed by a facile in situ photosynthesis approach. Systematic investigations reveal that the CoP nanoparticle can work as co‐catalyst to not only extract photogenerated electrons effectively from MAPbI3 to improve the photoinduced charge separation, but also facilitate the interfacial catalytic reaction. As a result, the as‐achieved MAPbI3/CoP hybrid displays a superior H2 evolution rate of 785.9 µmol h−1 g−1 in hydroiodic acid solution within 3 h, which is ≈8.0 times higher than that of pristine MAPbI3. Furthermore, the H2 evolution rate of MAPbI3/CoP hybrid can reach 2087.5 µmol h−1 g−1 when the photocatalytic reaction time reaches 27 h. This study employs a facile in situ photosynthesis strategy to deposit the metal phosphide co‐catalyst on halide perovskite nanocrystals to conduct photocatalytic H2 evolution reaction, which may stimulate the intensive investigation of perovskite/co‐catalyst hybrid systems for future photocatalytic applications.

Solar-Driven Hydrogen Generation by Metal Halide Perovskites: Materials, Approaches, and Mechanistic View

“…Through PL measurements, the quenching of the PL signal was considered as an indicator of effective charge transfer in the composite catalysts which was further corroborated by the much shorter PL lifetime (τ avg ) of MAPbI 3 /CoP (148.1 ns) with respect to the pristine MAPbI 3 (232.6 ns). 15 The further confirmation of the effective charge transfer and separation process in the composite was achieved by measuring the surface photovoltage (SPV) of pristine perovskite and of MAPbI 3 /CoP. A distinct negative signal found in the composite, with respect to no difference observed in MAPbI 3 before and after illumination, confirmed the electron accumulation of the surface of CoP nanoparticles during illumination.…”

“…(h) Schematic diagram of the fabrication and photocatalytic H 2 evolution process of the MAPbI 3 /CoP hybrid heterojunction. For details, see ref ( 15 ). Reprinted with permission from ref ( 15 ).…”

“… 15 MAPbI 3 nanocrystals were first prepared by the microcrystalline-assisted antisolvent method, and then the MAPbI 3 /CoP hybrid was synthesized by the in situ photodeposition process in which CoCl 2 and NaHPO 2 were dissolved in MAPbI 3 -saturated HI solution to work as the precursor solution. 15 TEM analysis revealed the presence, on the cubic-shaped crystals of the perovskite, of fine particles of CoP. Figure 2 h reports a schematic diagram of the fabrication and photocatalytic hydrogen evolution of the MAPbI 3 /CoP hybrid heterojunction.…”

“…Under visible light illumination, the photocatalytic HER rate of the optimal composite (MAPbI 3 :CoP 1:0.25) was 785.9 μmol g –1 h –1 , that is, ≈8.0 times higher than that of pristine MAPbI 3 . 15 The authors proposed that CoP nanoparticles not only favored the charge separation but also contributed in increasing the number of reaction active sites. Through PL measurements, the quenching of the PL signal was considered as an indicator of effective charge transfer in the composite catalysts which was further corroborated by the much shorter PL lifetime (τ avg ) of MAPbI 3 /CoP (148.1 ns) with respect to the pristine MAPbI 3 (232.6 ns).…”

“…A distinct negative signal found in the composite, with respect to no difference observed in MAPbI 3 before and after illumination, confirmed the electron accumulation of the surface of CoP nanoparticles during illumination. 15 Finally, the long-term stability of the photocatalytic activity of the composite was measured under continuous illumination for 27 h (differently from most of the works measuring the stability over cycles). The crystalline structure and the HER activity was maintained during this time course as well as for five successive cycles.…”