Charge-transfer regulated visible light driven photocatalytic H<sub>2</sub> production and CO<sub>2</sub> reduction in tetrathiafulvalene based coordination polymer gel.

Verma, Parul; Singh, Ashish; Rahimi, Faruk Ahamed; Sarkar, Pallavi; Nath, Sukhendu; Pati, Swapan Kumar; Maji, Tapas Kumar · Nat Commun · 2021

basic_science · Level V

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Abstract

The much-needed renewable alternatives to fossil fuel can be achieved efficiently and sustainably by converting solar energy to fuels via hydrogen generation from water or CO<sub>2</sub> reduction. Herein, a soft processable metal-organic hybrid material is developed and studied for photocatalytic activity towards H<sub>2</sub> production and CO<sub>2</sub> reduction to CO and CH<sub>4</sub> under visible light as well as direct sunlight irradiation. A tetrapodal low molecular weight gelator (LMWG) is synthesized by integrating tetrathiafulvalene (TTF) and terpyridine (TPY) derivatives through amide linkages and results in TPY-TTF LMWG. The TPY-TTF LMWG acts as a linker, and self-assembly of this gelator molecules with Zn<sup>II</sup> ions results in a coordination polymer gel (CPG); Zn-TPY-TTF. The Zn-TPY-TTF CPG shows high photocatalytic activity towards H<sub>2</sub> production (530 μmol g<sup>-1</sup>h<sup>-1</sup>) and CO<sub>2</sub> reduction to CO (438 μmol g<sup>-1</sup>h<sup>-1</sup>, selectivity > 99%) regulated by charge-transfer interactions. Furthermore, in situ stabilization of Pt nanoparticles on CPG (Pt@Zn-TPY-TTF) enhances H<sub>2</sub> evolution (14727 μmol g<sup>-1</sup>h<sup>-1</sup>). Importantly, Pt@Zn-TPY-TTF CPG produces CH<sub>4</sub> (292 μmol g<sup>-1</sup>h<sup>-1</sup>, selectivity > 97%) as CO<sub>2</sub> reduction product instead of CO. The real-time CO<sub>2</sub> reduction reaction is monitored by in situ DRIFT study, and the plausible mechanism is derived computationally.