Metal Mesh and Narrow Band Gap Mn0.5Cd0.5S Photocatalyst Cooperation for Efficient Hydrogen Production

Abstract

A novel co-catalyst system under visible-light irradiation was constructed using high-purity metal and alloy mesh and a Mn0.5Cd0.5S photocatalyst with a narrow band gap (1.91 eV) prepared by hydrothermal synthesis. The hydrogen production rate of Mn0.5Cd0.5S changed from 2.21 to 6.63 mmol·(g·h)−1 with the amount of thioacetamide, which was used as the sulphur source. The introduction of Ag, Mo, Ni, Cu, and Cu–Ni alloy meshes efficiently improved the H2 production rate of the co-catalyst system, especially for the Ni mesh. The improvement can reach an approximately six times greater production, with the highest H2 production rate being 37.65 mmol·(g·h)−1. The results showed that some bulk non-noble metal meshes can act as good or better than some noble metal nanoparticles deposited on the main photocatalyst for H2 evolution due to the promotion of photoinduced electron transfer, increase in redox reaction sites, and prevention of the recombination of carriers.

Highly Water-Stable and Efficient Hydrogen-Producing Heterostructure Synthesized from Mn0.5Cd0.5S and a Zeolitic Imidazolate Framework ZIF-8 via Ligand and Cation Exchange

“…In addition to the (002) plane, we observed the (101) and (100) crystal planes of the MCS material, corresponding to lattice spacings of 0.31 and 0.35 nm (Figure S1d,e), respectively. Because the MCS solid solution is formed by the dissolution of Mn atoms in CdS, the lattice distortion caused by the solute atoms of Mn provides the shear stress for the occurrence of the dislocation motion. , The dislocations observed in the (101) and (100) crystal planes (Figure S1d,e) provide sufficient evidence for the successful synthesis of the MCS material . Notably, the mappings of Cd and Mn in Figure o,p show that these elements are more distributed in the periphery, while Br is mainly distributed in the central region (Figures n and S2i).…”

“…Mn 0.5 Cd 0.5 S (referred to as MCS henceforth) was synthesized using a one-pot solvothermal process. ,, In 40 mL of deionized water, 1 mmol of Mn­(Ac) 2 ·4H 2 O and 1 mmol of Cd­(Ac) 2 ·2H 2 O were dissolved, and the resulting solution was denoted as solution A. Meanwhile, 6 mmol of TAA was added into 40 mL of deionized water, and the pH value of the solution was adjusted to 10.5 using NaOH (6 mol/L), and this solution was denoted as solution B.…”

“…13 The characteristic peaks appear at 2θ = 26.7, 44, and 52.33°c orresponding to the (002), (110), and (112) crystal faces of the MCS, respectively. 1,8,17,24,25,27 Compared with the strong peak intensity of MCS, the diffraction peaks of ZIF-8 are not reflected in the XRD spectra of MCS@ZIF-Mn, MCS@ZIF-Br, and MCS@ZIF-MB. This is most likely because of the low ZIF-8 content along with its highly dispersed crystals.…”

“…1,9 The dislocations observed in the (101) and (100) crystal planes (Figure S1d,e) provide sufficient evidence for the successful synthesis of the MCS material. 17 Notably, the mappings of Cd and Mn in Figure 2o,p show that these elements are more distributed in the periphery, while Br is mainly distributed in the central region (Figures 2n and S2i). This phenomenon not only shows that the surface of ZIF-8-MB is coated with MCS but also provides evidence for the successful synthesis of ZIF-8-MB.…”

“…Compared with other conventional metal sulfides such as CdS, its band gap can be easily adjusted by changing the value of x to meet the requirements of photocatalytic hydrogen release. ,,− , In 2009, Ikeue, et al reported that the Mn x Cd 1– x S ( x ≈ 0.1) solid solution demonstrates better hydrogen production activity and photocorrosion tolerance than CdS as well as other binary S-based catalytic materials. Our previous research has shown that the Mn x Cd 1– x S solid solution exhibits significant photocatalytic hydrogen production activity and good photocatalytic stability by adjusting the addition of thioacetamide (TAA). Although the conduction band (CB) position and band gap of Mn x Cd 1– x S solid solution can be modified to improve the photocatalytic performance, the rapid complexation of photoexcited charge carriers is still a major issue limiting its practical application.…”