A differential photoelectrochemical hydrogen peroxide sensor based on catalytic activity difference between two zeolitic imidazolate framework surface coatings

Improvement of the sensitivity and selectivity is important in the development of an analytical method. Herein, we propose a differential photoelectrochemical (PEC) sensor to hydrogen peroxide based on the catalytic activity difference between two zeolitic imidazolate framework (ZIF) surface coatings. In the sensing and reference photoelectrodes, ZIF-67 and ZIF-8 films were grown on the surface of carboxylated carbon nanotubes-graphite-like carbon nitride/TiO2 nanotube array, respectively. The molecular sieve effect of ZIF-8 and ZIF-67 coatings can prevent the diffusion of molecules with size larger than the pores in coating layers (e.g. ascorbic acid), improving the selectivity of the PEC sensor to H2O2. The sensing photoelectrode offers higher sensitivity to H2O2 than the reference one due to the excellent catalytic activity of ZIF-67. The interference from the surfaces of the sensing and reference photoelectrodes can be eliminated effectively by the differential strategy, enhancing further the selectivity, reliability and stability of the sensor. Under optimized conditions, the as-prepared differential PEC sensor was applied to the detection of H2O2 with limit of detection of 1.5 nM, exhibiting high sensitivity and anti-interference ability.