C-ZIF-8 modified NiO photocathode and enhanced photosensitizer signal amplification for ultra-sensitive photoelectrochemical detection of lead ions†

Abstract

NiO photocathodes have been developed for photoelectrochemical (PEC) sensing. However, the development of NiO-based photoactive materials with higher performance is still being pursued to further improve the sensitivity of detection. In this article, we prepared a C-ZIF-8/NiO composite material photocathode composed of porous carbon derived from ZIF-8 (C-ZIF-8) and NiO, and utilized its enhanced PEC activity and amplification effect on chlorohemin (hemin) sensitization to achieve ultra-sensitive detection of lead ions (Pb²⁺). The introduction of C-ZIF-8 improved the charge transfer and light absorption ability of the composite material, and significantly increased the load of hemin on the photocathode, thereby enhancing the photocurrent response by 8 times. Based on the C-ZIF-8/NiO photocathode and in situ generated photosensitizer signal amplification strategy, ultra-sensitive detection of Pb²⁺ had been attained with a detection linear range of 10 pM to 5 nM and a detection limit of 2.6 pM. This study provides a new platform for high sensitivity detection of Pb²⁺, and extensive potential applications could be further expected.