Bifunctional WO3 microrods decorated RGO composite as catechol sensor and optical limiter

Highlights: • Herein we report, the bifunctional catechol sensing and optical limiting properties of hexagonal WO₃ and RGO composites. CV and DPV data disclose the superior sensing performance of composite electrode in the case of oxidation current, sensitivity, detection limit and stability. • Combination of 1D and 2D structures in WO3/RGO composite provides more active surface area for the catechol adsorption and their synergistic interaction helps to achieve the superior current sensitivity than the pristine WO₃. • Overall analytical results suggest that the ease of synthesis and high current sensitivity make the prepared composite as a viable electrode material for the sensing applications. • From theoretical simulations, stronger bonding and higher charge transfer from catechol on RGO supported system signifies its higher catechol sensitivity justifying the experimental observations. • For the nonlinear optical properties, z-scan measurement is performed in OA mode to estimate the nonlinear absorption coefficient β of WO₃ samples. Based on the NLO results (RSA and self-defocusing) obtained in the present study, WO₃/RGO composite can be utilized in the optical limiting applications to protect the sensitive devices from strong laser beam. Herein, we report the one-pot synthesis of WO₃/RGO composite and its efficient electrochemical activity in catechol (CC) oxidation. Anchoring of 1-D WO₃ microrods on 2-D RGO nanosheets were confirmed through the detailed physicochemical analyses (XRD, FESEM, XPS, Raman). Availability of large electrocatalytically active surface area yields the conductivity enrichment as well as significantly improved redox properties in WO₃/RGO composite. Further, a 20-fold intensified oxidation signal in CV and a 4-fold increased sensitivity from differential pulse voltammetry (DPV) support the superior electron transfer rate at the surface of WO₃/RGO composite. Oxidation of CC involving the transfer of two electrons via a diffusion controlled process was revealed by the electrochemical approaches. From density functional theory (DFT) simulations, the charge transfer from O 2p orbital of catechol to W 4d orbital of WO₃ facilitate the oxidation of catechol molecule. Z-scan study explored the strong reverse saturable absorption at 532 nm excitation and the third-order nonlinear optical susceptibility χ⁽³⁾ of 9.727 × 10⁻⁸ esu was obtained for WO₃/RGO. Hence, the hydrothermally prepared WO₃/RGO composite with its excellent redox properties and negative nonlinearity could be a competent material to use in electrochemical sensing and optical limiting.