Green and sustainable synthesis of TPD-based donor-acceptor-type conjugated polymer photocatalysts for hydrogen production under visible light

Donor (D)-acceptor (A) structured conjugated polymers (CPs) have attracted increased attention owing to their application in efficient photocatalytic hydrogen production from water, benefiting from their unique advantages of high charge mobility, strong light-harvesting ability, and tunable band gaps. As a typical "A" building block to construct D-A type CPs, thieno[3,4-c]pyrrole-4,6-dione (TPD) may bind co-catalyst, similar to Pt though the sigma-pi anchor of its carbonyl group with Pt to enhance the performance of solar-driven hydrogen production. Herein, we developed three TPD-based D-A-type CPs, namely, TPD2T, TPDTT, and TPDBDT, using 2,2 '-bithiophene (2T), cyclopenta[2,1-b:3,4-b]dithiophene (TT), and benzo[1,2-b:4,5-b]dithiophene (BDT) as "D" units, via direct C-H/C-H coupling polycondensation, offering an atom-economic and eco-friendly way to achieve new CP materials for highly effective hydrogen evolution. Among them, TPDBDT-based nanoparticles exhibited the highest photocatalytic activity with remarkable hydrogen evolution rates of 1819.4 mu mol h-1 g-1 and 7420.0 mu mol h-1 g-1 in the absence and presence of co-catalyst Pt, respectively. The mechanism of the hydrogen production of TPD-based polymers was discussed based on DFT calculations. This work not only demonstrates the first example of CPs synthesized via C-H/C-H cross-coupling polymerization for application in water splitting for hydrogen production but also helps to understand the relationship between polymer structure and photocatalytic hydrogen production performance. The conjugated polymers are synthesized via greener direct C-H/C-H cross-coupling polycondensation for application in photocatalytic hydrogen production.