Triindole-based donor-π-acceptor conjugated polymers for efficient photocatalytic hydrogen evolution: enhancing...

Donor-π-acceptor (D-π-A) conjugated polymers are promising photocatalysts for water splitting. Their π-bridges promote intramolecular charge transfer (ICT), leading to better charge separation and enhanced activity. However, further improvements can be achieved by carefully choosing donor units and optimizing building block combinations. In this study, five conjugated porous polymers (CPPs) were synthesized via Still/Suzuki coupling reactions, including ternary polymers with varying donor-to-acceptor ratios and binary polymers for comparison. Photocatalytic hydrogen production (PHP) tests showed that the ternary polymer TATTS-1 achieved the highest hydrogen evolution rates (HER) of 130.56 and 172.75 mmol g^-1 h^-1 under visible light and full arc irradiation, respectively. Kelvin probe force microscopy (KPFM) and femtosecond transient absorption (fs-TA) spectroscopy measurements confirmed that the adoption of the D-π-A configuration can facilitate charge separation, suppress recombination, and enhance transfer efficency, which was also confirmed by theoretical calculations. These findings underscore the superior performance of the D-π-A configuration over conventional Donor-acceptor (D-A) systems in designing efficient polymer-based photocatalysts, and highlighting the synergy of triazatruxene (TAT) donor, thiophene π-bridge, and dibenzothiophene sulfone (BTDO) acceptor in building efficient hydrogen evolution photocatalysts.