3D NiO nanoflakes/carbon fiber meshwork: Facile preparation and utilization as general platform for photocathodic bioanalysis

Highlights: • 3D NiO nanoflakes/carbon fiber meshwork was fabricated. • Sensitive cathodic PEC enzymatic bioanalysis was thus achieved. • This elegant sensing of ALP demonstrated high sensitivity, selectivity and stability. • It could be used as general cathodic photoelectrochemical bioanalysis platform. Herein, we describe a customized approach for facile preparation of three-dimensional (3D) NiO nanoflakes (NFs)/carbon fiber meshwork (CFM) and its validation as a common photocathode matrix for photoelectrochemical (PEC) bioanalysis, which to our knowledge has not been reported. Specifically, 3D NiO NFs/CFM was fabricated by a sequential liquid phase deposition and annealing process, which was then characterized by scanning electron microscopy, X–ray photoelectron spectrum, UV–vis absorption spectra and N₂ adsorption-desorption measurement. Sensitized by BiOI and incorporated with an alkaline phosphatase (ALP)/tyrosinase (TYR) bi-enzyme cascade system, a sensitive split-type cathodic PEC bioanalysis for the determination of ALP was achieved. This method can detect ALP concentrations down to 3 × 10⁻⁵ U L⁻¹ with a linear response range of 0.001–10 U L⁻¹. Moreover, this proposed system exhibited good selectivity, stability and excellent performance for real sample analysis. This research features the facile preparation of 3D NiO NFs/CFM that could acts as a universal matrix for photocathodic analysis, and is envisioned to stimulate more effort for advanced 3D photocathode for PEC bioanalysis and beyond.