Enhancing the photoelectrochemical hydrogen evolution activity of polyaniline through small molecular acid doping to introduce polariton-enhanced active sites

Development of organic polymer photoelectrodes with high surface activity is the key to efficient water splitting for hydrogen production. Polyaniline (PANI) prepared under alkaline conditions has semiconducting properties, but high reaction rates are difficult to achieve due to its poor surface activity. In this study, electrochemical doping was used to introduce small molecular acids (2,3-hydroxybutanedioic acid (TA), 2-hydroxybutanedioic acid (MA), and succinic acid (SA)) containing different numbers of hydroxyl groups into the PANI backbone to form polarizers, dipolarizers and active sites. Density Functional Theory (DFT) shows that small molecular acids interact with the imine (=N-) structure of the PANI backbone via electron cloud stacking to form complex active sites. Meanwhile, the transition from polarons to dipolarons under light conditions increases the polarity of the PANI molecular chain, which further improves the photoelectrocatalytic performance. This study will bring new ideas for efficient photoelectrocatalysis based on organic polymers.