Photocatalytic Performance of NiS/CdS Composite with Multistage Structure

Abstract

Construction of heterojunctions between semiconductors is a significant way to promote the photocatalytic performance by improving the photogenerated charge separation. Herein, CdS with multistage structures (sphere, flower, and wheat) were first synthesized, and their photocatalytic activities of hydrogen production were not too high as massive electrons and holes are rapidly recombined. NiS/CdS composites were then prepared by depositing NiS nanofragments on the CdS surface, which exhibited higher photocatalytic activity (about 13-fold) than pure CdS. The enhanced reason is the effective charge separation and transfer (Z-scheme charge migration) formed between p-type NiS and n-type CdS, which is confirmed by Mott− Schottky plots and density of states. Moreover, the NiS/CdS composite shows much more efficient charge transfer than pure CdS, indicated by photocurrent response and photoluminescence. Therefore, this study offers an important strategy for the design of multistage structural photocatalysts with a p−n heterojunction to improve the charge separation.

Construction of NiPx/MoS2/NiS/CdS composite to promote photocatalytic H2 production from glucose solution

“…As the electrons at the CB position of CdS will combined with the holes at the VB position of NiS, the electrons on the CB position of NiS and the holes on the VB position of CdS are separated and performed longer lifetimes. This Z‐Scheme transfer route of NiS/CdS may be formed and beneficial for the charge transfer, which was verified by our previous work 36 . Thus, the photogenerated electrons can transfer from the CB position of CdS to the VB position of NiS (pathway 1).…”

“…This Z-Scheme transfer route of NiS/CdS may be formed and beneficial for the charge transfer, which was verified by our previous work. 36 Thus, the photogenerated electrons can transfer from the CB position of CdS to the VB position of NiS (pathway 1). As the CB positions of MoS 2 and NiP x are estimated to be -0.16 and -0.35 V, the electrons can transfer from CdS to MoS 2 and NiP x due to their less negative potential (pathway 2 and 3).…”

Study on the performance of a MOF-808-based photocatalyst prepared by a microwave-assisted method for the degradation of antibiotics

“…Therefore, the introduction of a new energy band into band gap and other energy band engineering is a basic strategy to improve the photocatalytic activity. 20 In this paper, MOF-808 with a large specic surface area and high stability was prepared simply and quickly by using a microwave oven. According to the previously reported literature, 21,22 the Bi 2 S 3 /MOF-808 composite was then prepared by a hydrothermal method and applied to the photocatalytic degradation of tetracycline.…”

Visible-light-driven hydrogen evolution from waste toner powder activated by Ni species

“…Furthermore, it is known that the Ni species could work as active sites to improve the activity of catalysts, even if the amount of the Ni species was small. 13,14,16,19,20 The results in our work indicate that the metallic Ni and NiO in the Ni species worked in synergy to facilitate H 2 production. As depicted in Scheme 2, the work function vs. vacuum of EY molecules at the HOMO and LUMO are respectively about −5.60 eV and −3.45 eV, 21 while the work function of metallic Ni is about −4.5 eV.…”

“…Moreover, we coupled waste toner powder with a Ni species, given the positive effect of Ni-based cocatalysts on enhancing the activity of photocatalysts for the HER reaction. 11–15 Here, it is found that, when activated by the Ni species, the hydrogen evolution rate of the pristine waste toner could achieve 944 μmol g −1 in 2 h, which was about 62 times higher than that of the pristine waste toner. The role of the Ni species in activating the waste toner is discussed in detail in this work.…”