Hierarchical Co₉S₈/ZnIn₂S₄ Nanoflower Enables Enhanced Hydrogen Evolution Photocatalysis

Abstract

Photocatalytic water splitting with clean solar energy is a sustainable way to produce green hydrogen (H2) fuel. Here, an efficient, visible-light-responsive hierarchical Co9S8/ZnIn2S4 photocatalyst is designed by decorating Co9S8 nanoparticles on ZnIn2S4 nanoflower through a two-step solvothermal process for photocatalytic H2 evolution. Two photoactive sulfide–sulfide integrations in a stable, hierarchical, and flower-like Co9S8/ZnIn2S4 heterojunction, provide large surface areas with rich active centers and endow a quick separation and transfer of photoinduced electrons and holes. With the optimal loading amount of Co9S8, the Co9S8/ZnIn2S4 photocatalyst, under visible-light illumination, free of any cocatalysts, reaches a high hydrogen evolution rate of 126.7 μmol h–1 or 12.67 mmol h–1 g–1 with high stability, which is 6 times higher than that of individual ZnIn2S4. Our effort may give some inspirations to the delicate design of competent novel structured photocatalysts for reinforcing photocatalytic performance.

Synthesis and Photocatalysis of Metal Oxide Aerogels: A Review

“…Steam methane reforming (SMR) contributes the majority (over 90%) of the produced H 2 , while water electrolysis contributes the rest. Photocatalytic water splitting can produce H 2 directly from H 2 O with the assistance of solar light, which is the most promising way to address the energy crisis challenge. − In a recent review paper by Wu et al, the band structure of several semiconductors’ photocatalysts was analyzed. Metal oxides such as TiO 2 , BiVO 4 , In 2 O 3 , NiO, and ZnO can be considered as candidates for photocatalysts because their band structure fulfills the requirements, that is, the bandgap is greater than 1.23 eV, and the conduction band is more negative than the one of the H 2 generation potential and the valence band is more positive than the one of the O 2 generation potential.…”

Boosting the photocatalytic activity of ZnIn2S4-based photocatalyst for H2 evolution using porous ZnWO4 nanoflakelets as a cocatalyst

“…[3][4][5][6] Among them, cocatalyst loading is one of the most powerful and popular strategies. Although plenty of cocatalysts, such as Cu 3 P, 7 Co 9 S 8 , 8 MoS 2 -graphene, 9 NiS, 10 and a-MnO 2 /Ag, 11 have been developed, the expected improvement in the catalytic efficiency of ZnIn 2 S 4 has not been achieved. 12 The key issue behind the limited enhancement in catalytic performance via cocatalyst loading can be attributed to the fact that there are only a few contact sites between the cocatalyst and the main ZnIn 2 S 4 , which hinders the electronic transfer process and prevents the cocatalyst from realizing its full potential, ultimately resulting in a failure to achieve the expected improvement in catalytic efficiency.…”

Co–P bond effect on an MOF-derived Co9S8hollow polyhedron supported Ni2P co-catalyst for efficient photocatalytic hydrogen evolution

“…Among them, due to its high flat band potential, unique electronic properties and good stability, noble metal free Co 9 S 8 shows great application prospects in photocatalysis. 34 A transition metal phosphide can be used as a cocatalyst to promote the separation and transfer of electron-hole pairs, so it has been widely used in the field of photocatalysis and electrocatalysis. However, its widespread use is limited by the natural scarcity of rare metals.…”

“…Among them, due to its high flat band potential, unique electronic properties and good stability, noble metal free Co 9 S 8 shows great application prospects in photocatalysis. 34…”