Sensor surface via inspiration from Nature: The specific case of electron trapping in TiO2/WO3(∙0.33H2O) and reaction center/WO3(∙0.33H2O) systems

Inspiring from RCs/WO3(·0.33H2O) biohybrid systems, TiO2/WO3(·0.33H2O) inorganic systems were designed with highly efficient sensorial applicability. The promising peculiarities of biohybrid and inorganic composites is given by the involvement of WO3(·0.33H2O) as efficient charge separator. [Display omitted] •The anchoring capacity of WO3⋅0.33H2O was assigned to the presence of W=O and O-H.•The efficiency of detection and degradation is directly correlated to W5+ content.•pH has a significant influence on the interactions’ type between WO3 and RCs.•Synergic stabilization of light separated charges was employed by WO3/RCs.•Flash kinetics and fluorescence explained the ability of WO3 as e- trap in WO3/RCs. In this work, reaction center protein (RC) isolated from Rhodobacter sphaeroides purple bacteria was coupled with WO3(∙0.33H2O) via physical adsorption, where vectorial electron transfer (from RCs towards the inorganic carrier) was demonstrated using flash kinetics and photoluminescence measurements. The efficiency of the interaction between RCs and WO3(∙0.33H2O) was correlated to the components’ surface charge at the working pH and the structural/morphological and surface properties of the inorganic carrier (e.g., anchoring capacity assured by HO, WO bonds). The role of WO3(∙0.33H2O) as final electron trap and charge separator was proven not only in RCs/WO3(∙0.33H2O) biohybrid systems but also in TiO2/WO3(∙0.33H2O) composites. The charge transfer in the inorganic composites was evaluated by monitoring the reverse process of the color reaction (W5+ → W6+) via diffuse reflectance spectroscopy (DRS) after a previous UV-A (320–400 nm) exposure. The efficiency of the charge transfer process in inorganic systems was correlated to the initial W5+ content of WO3(∙0.33H2O), followed by the photocatalytic efficiency evaluation of these inorganic composites under UV-A irradiation.