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Highly active and durable hydrogen evolution reaction (HER) catalysts are required for the low-cost and high-yield generation of clean energy from water splitting. Herein, a Cu3BiS3/TiO2 (C@T) heterojunction film is constructed by a facile dip-coating method for the synthesis of Cu3BiS3 nanorods on a TiO2 film. The heterojunction film is used as a catalyst in water splitting which exhibits a higher photoelectrochemical (PEC) performance and electrocatalytic activity than the respective pure Cu3BiS3 nanorods counterpart. Experimental results confirm that the PEC performance of the C@T heterojunction film displays a strong photoresponse of as high as ∼1.5 × 10−4 A cm−2 at an applied potential of −0.5 V vs. Ag/AgCl under visible light irradiation. What's more, the as-prepared C@T film shows the best electrocatalytic performance with an onset overpotential of 150 mV, a low Tafel slope of 42.67 mV dec−1, a large current density of 10.8 mA cm−2 at an overpotential of 220 mV, and a remarkable cycling stability. The enhanced PEC performance is associated with the formation of a heterojunction structure at the interface between TiO2 and Cu3BiS3, which facilitates light absorption and separation of photogenerated charge carriers. The growth of Cu3BiS3 nanorods on a TiO2 film modified the electronic structure and increased the electrochemical area, and thus is responsible for enhanced catalytic activity. Benefitting from its scalable preparation and properties, the Cu3BiS3 nanorods/TiO2 heterojunction film is indeed a promising catalyst for hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

La2Ti2O7 has been perceived as a potential photocatalytic material candidate for hydrogen evolution in recent years. However, its wide band gap brings about a narrow light absorption range and thereby results in poor photocatalytic activity. Herein, to enhance the light absorption capability, as well as promote the separation of photogenerated carriers, a CuInS2/La2Ti2O7 heterojunction photocatalyst was designed. A narrow band-gap semiconductor, CuInS2, was grown in situ on the surface of La2Ti2O7 by a solvothermal method. The effects and related mechanisms of CuInS2 loading on the photocatalytic activity were systematically investigated. The composite photocatalysts present a much better hydrogen evolution performance than the single materials. The highest hydrogen evolution rate reaches 64.41 μmol g−1 h−1. The enhancement of hydrogen evolution performance can be ascribed to the improvement of light absorption, as well as the acceleration of separation of photogenerated carriers, due to the loading of CuInS2 and the formation of a type II heterojunction between two materials. [ABSTRACT FROM AUTHOR]

Layered perovskite-type semiconductor La2Ti2O7 has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La2Ti2O7 with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co3O4 nanoparticles on the surface of n-type plate-like La2Ti2O7. The effects of Co3O4 loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co3O4/La2Ti2O7 possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co3O4 exhibits the highest hydrogen evolution rate of 79.73 μmol·g−1·h−1 and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co3O4 ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La2Ti2O7-based heterojunctions for photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

The design of highly efficient and stable photoelectrocatalysts for the hydrogen evolution reaction (HER) is critical to the large-scale application of clean hydrogen energy. Here, Cu3BiS3 nanoflowers (NFs) with photoelectrochemical (PEC) activity were synthesized via a solvothermal method under mild and low-toxic reaction conditions, and the Au nanoparticles (Au NPs) were loaded onto Cu3BiS3 NFs to improve the photoelectrocatalytic performance. Compared with pure Cu3BiS3 NFs, Au-Cu3BiS3 composites (A@C) exhibit a much higher photocurrent density (2 × 10−4 A cm−2) and greatly enhanced photoelectrocatalytic activity (2.31 μmol h−1), which are attributed to the enhancement in electron capture abilities, active sites and visible light absorption from the localized surface plasmon resonance effect (LSPR) of Au NPs. Furthermore, the excellent conductivity of Au NPs can effectively accelerate the separation and collection of photogenerated carriers. This work highlights a feasible strategy to improve the PEC activity of the Cu3BiS3 photoelectrocatalyst, and confirms the great potential of Au-Cu3BiS3 composites for hydrogen evolution applications. [ABSTRACT FROM AUTHOR]

In this article, a novel Ag2S nanoparticle-decorated MoS2 composite (A@M) was synthesized through a facile in situ growth of the monoclinic crystallographic Ag2S on MoS2 nanosheets. The A@M composite was used as a catalyst in water splitting which exhibits higher electrocatalytic and photoelectrocatalytic activity than the respective pure MoS2 and Ag2S counterparts. Experimental results indicate that the as-prepared A@M composite with an optimal Ag2S/MoS2 molar ratio of 16.30% (16%A@M) shows the best catalytic performance with low overpotentials (110 mV for Voc, 190 mV for onset overpotential, 208 mV for the current density of 20 mA cm−2), a small Tafel slope (42 mV dec−1), and a high photocurrent (82 μA cm−2 under an applied potential of 0.4 V). The enhanced electrocatalytic activity is associated with the improved electrical conductivity resulting from the stretched MoS2 nanosheets and the enriched active sites due to the decorated Ag2S particles. The formation of a type II heterojunction structure at the interface between Ag2S and MoS2 facilitates the separation of photogenerated charge carriers, and thus is responsible for the enhanced photoelectrocatalytic activity and photocatalytic H2 production rate (628 μmol h−1 g−1). This work suggests a promising choice to overcome the intrinsic drawbacks of MoS2 nanostructures for the application in hydrogen evolution. [ABSTRACT FROM AUTHOR]