Photoelectrochemical Catalytic Performance Of MoS₂ Based Hybrid For Hydrogen Evolution Reaction

Hydrogen is expected to be a kind of new energy because of its high energy density and wide-availability in nature. However, traditional hydrogen production methods bring a lot of problems, such as energy consumption and environmental issues. Recently, hydrogen evolution through photoelectro-chemical attracts much attention because of its high efficiency and low-cost. For this method, photoelectrochemical catalysts play an important role in enhancing the utilization of sunlight, reducing the overpotential of hydrogen evolution reaction and decreasing the energy consumption. Therefore, design of the catalysts for photoelectrochemical hydrogen evolution is of vital importance. This paper mainly concerns about the structural design and hybrid of catalyst materials, including the influence of catalysts on the performance of the photoelectrochemical hydrogen evolution. The main research contents are as follows:1. The two-step electrodeposition method was applied to prepare the CdS/MoS₂ bilayer structure, and a simple spin-coating process followed with an electrochemical deposition was performed to prepare another three composite catalysts, including GO/MoS₂ ?graphene oxide?, N-rGO/MoS₂ ?Nitrogen-doped reduced graphene oxide? and MoS₂/N-rGO. Their photoelectrochemical performances of hydrogen evolution were tested, and the results showed that the electrochemical catalytic performance of the four bilayer structures are much better than pure MoS₂ in both alkaline and acid solution, while their photocatalytic activity are quite poor.2. Based on the previous work, a simple hydrothermal method followed with an electrochemical deposition was applied to prepare CdS@MoS₂ core-shell nanorod arrays to improve the photoelectrochemical catalytic performance. By adjusting the hydrothermal time of CdS and deposition time of MoS₂, the morphology of core-shell structures can be controlled. It was found that the CdS nanorod arrays, whose length increased with the increase of hydrothermal time, mainly contributed in the photocatalytic activity, while the MoS₂ shell highly influenced the electrocatalytic performance. Furthermore, we found that P-N heterostructures are formed between CdS and MoS₂. During the photoelectrochemical hydrogen evaluation process, both forward bias and reverse bias can be applied to the surface of the catalyst, which are attributed to the superior photocatalytic and electrocatalytic performance of CdS@MoS₂ core-shell nanorod arrays.3. To optimize the catalytic activity of CdS@MoS₂ core-shell structures, we prepared CdS@MoS₂/N-rGO ternary catalysts by using spin-coating. From the polarization curves for hydrogen evolution, we can see that, in acid medium, the current density in dark and under simulated solar light are 35.88 mA.cm-2 and 46.88 mA.cm-2 under -0.8V ?vs SCE?, which is 2 times and 1.6 times that of CdS@MoS₂ core-shell nanorod arrays, respectively. This result indicated that there is a synergistic effect between N-rGO and CdS@MoS₂ core-shell, which further improves the performance of photoelectrochemical hydrogen evaluation.