Our article on solar-energy-driven activation of C−H bond within alcohols and C−C coupling into diols has been published in Chem. Commun. and has been chosen as the Front Cover.
Chem. Commun., 2020, 56, 1776-1779.
Link: https://pubs.rsc.org/en/content/articlelanding/2020/CC/C9CC09205F
RSC英国皇家化学会报道：https://mp.weixin.qq.com/s/fWYD5g6eO7Ruc9fgWK3xPw
Our article also highlighted on the Home page of Chemical Communications Blog by Tianyu Liu.
Link: https://blogs.rsc.org/cc/2020/02/11/upgrading-methanol-using-zinc-indium-sulfide-and-solar-light/
Upgrading Methanol Using Zinc-Indium-Sulfide and Solar Light
11 Feb 2020
By Tianyu Liu. (He is a blog writer for Chem. Comm. and Chem. Sci.)
Based on the chemical formulae, can you figure out how to convert methanol (CH3OH) into ethylene glycol (HOCH2CH2OH)? If you have constantly practiced your organic chemistry, you might have already found the answer: combining two methanol molecules and eliminating one hydrogen molecule (H2). Indeed, this methanol-coupling reaction is a promising, low-cost chemical route to upgrade methanol to chemicals with more carbon atoms. The feasibility of this route, however, is low under mild conditions without catalysts to drive the reaction.
A group of scientists led by Shunji Xie and Ye Wang, both at Xiamen University, China, has developed an environmentally friendly catalyst, Zn2In2S5, for room-temperature methanol coupling to produce ethylene glycol using solar light. This work has been published in Chemical Communications (DOI: 10.1039/c9cc09205f).
The synthesized Zn2In2S5 catalyst is comprised of 1-3 layers of nanosheets. Through a hydrothermal reaction, the researchers first synthesized multi-layer Zn2In2S5 stacks in an aqueous solution (Fig. 1a). Subsequent ultrasonication exfoliated the stacks into few-layer Zn2In2S5 nanosheets that were confirmed by transmission electron microscopy (Fig. 1b). Zn2In2S5 is a semiconductor and its valence band (VB) resides below the redox potential of ethylene glycol/methanol (Fig. 1c). The band alignment enables Zn2In2S5 to catalyze the oxidation of methanol to ethylene glycol.
Figure 1. (a) A scheme of the synthesis procedures of few-layer ZnmIn2Sm+3 (m=1-3) nanosheets. (b) Transmission electron microscopy images of few-layer Zn2In2S5 nanosheets. (c) Positions of the valence bands (VBs) and conduction bands (CBs) of different metal-sulfide semiconductors.
Zn2In2S5 and its composite exhibited high catalytic activity. Upon irradiation with visible light and solar light (AM 1.5), photo-induced electrons and holes generated in Zn2In2S5 (Fig. 2a). The electrons reduced protons in electrolytes and liberated hydrogen gas, while the holes moved to the Zn2In2S5 surface and split the C—H bond of methanol, forming ·CH2OH radicals. These radicals then dimerized into ethylene glycol. Through depositing a hydrogen evolution co-catalyst, cobalt monophosphide (CoP), and illuminating using AM 1.5 solar light, the authors observed that the CoP/Zn2In2S5 catalyst achieved a rapid formation rate (18.9 mmol gcat-1 h-1) and high selectivity (~90%) of ethylene glycol (Fig. 2b). The yield of ethylene glycol after 12 h of reaction was 4.5%.
Zn2In2S5 was demonstrated to effectively catalyze C—H cleavages and C—C couplings of different alcohols, e.g., from ethanol to 2,3-butanediol.
To find out more, please read:
C–H Activations of Methanol and Ethanol and C–C Couplings into Diols by Zinc–Indium–Sulfide Under Visible Light
Haikun Zhang, Shunji Xie, Jinyuan Hu, Xuejiao Wu, Qinghong Zhang, Jun Cheng, and Ye Wang
Chem. Commun., 2020, 56, 1776-1779
