Simple synthesis and photoelectrochemical characterizations of polythiophene/Pd/TiO2 composite microspheres.

We report here a simple, effective, and low cost method to synthesize polythiophene/Pd/TiO2 (PTh/Pd/TiO2) ternary composite microspheres and apply such a composite to photoelectrochemical (PEC) sensing. TiO2 spherical aggregates of 200 nm diameter, consisting of nanoscale building blocks of TiO2, have been prepared by hydrolysis of tetrabutyl titanate in a water-in-oil emulsion system (Vwater/Vacetone=1/100). Pd species and PTh layer were decorated onto TiO2 microspherical substrates by reduction of Pd salts and polymerization of thiophene, respectively. The high surface area, effective charge transfer, and enhanced light absorption of the ternary composite could improve PEC performance under simulated sunlight. The sensitivity, selectivity, and stability of PEC sensor for detecting l-cysteine were much higher than those of the traditional electrochemical sensor. The detection limit of l-cysteine was 9.24 μM in the linear range of 0.31-5.30 mM. Moreover, the results also indicated a good anti-interference and acceptable accuracy in practical application, providing a rapid and sensitive detection method.