A highly sensitive photoelectrochemical biosensor for CEA analysis based on hollow NiS@NiO/TiO₂ composite with typal...

Heterostructured construction is regarded as a valuable approach to improve photoelectrochemical (PEC) performances. Herein, porous hollow NiS@NiO spheres were prepared derived from the Ni(TCY) MOFs precursor. Photoactive TiO₂ was coupled with as-prepared NiS@NiO to form a close heterojunction interface of NiS@NiO/TiO₂. NiS@NiO/TiO₂ modified ITO electrode (NiS@NiO/TiO₂/ITO) displayed fiercely enhanced photocurrent response, which was 4687-fold than that of NiS@NiO/ITO (0.008 μA) and 8.5-fold than that of TiO₂/ITO (4.41 μA), respectively. Remarkable PEC property could be ascribed to the hollow NiS@NiO spheres with thin-shell structure provided there is a larger active surface area for harvesting the visible light. Most importantly, the p-n type NiS@NiO/TiO₂ heterojunction could lead to generating more photo-excited charge carriers (e^-/h⁺) and efficiently hinder the recombination of carriers, resulting in significantly augmented photocurrent output. Based on this outstanding PEC property, NiS@NiO/TiO₂/ITO electrode fabricated sensing platform (BSA/anti-CEA/NiS@NiO/TiO₂/ITO, BSA=Bovine serum albumin) exhibited high sensitivity for monitoring CEA (Carcinoembryonic antigen). Wide linear detection range was from 0.001 to 45 ng mL^-1 and with a low detection limit of 1.67 × 10^-4 ng mL^-1 (S/N = 3). Prepared biosensors also showed good reproducibility, stability and had satisfying specificity. Thus, the proposed NiS@NiO/TiO₂ heterostructured composite afforded well-design and synthesis strategy for constructing high-performance photoactive materials from MOFs-derivate.