Electrochemical oxidation method on anatase-to-rutile phase transition to construct TiO2 nanosheets-based sensitive biosensing platform towards biomolecules

TiO 2 nanosheets with rutile as the principle crystalline phase were prepared through the in-situ electrochemical oxidation of Ti 3 C 2 T x nanosheets. • Electrochemical transformation method exhibits higher efficiency in inducing the anatase-to-rutile phase transition than the conventional method of high-temperature heating. • Our study elucidates the mechanism underlying the structural evolution and phase transition in TiO 2 nanosheets from a thermodynamic perspective, offering valuable insights for the rational design of biosensing platforms towards biomolecules. Two-dimensional TiO 2 nanosheets (NS) enable efficient stabilization of aptamers and enhanced electron transfer on electrode surface for electrochemical biosensing applications. However, the effect of morphology and crystalline phase of TiO 2 NS on its detection performance towards biomolecules are unclear. Meanwhile, the mechanism underlying the structural evolution and anatase-to-rutile phase transition in TiO 2 NS via electrochemical transformation remains elusive. Thus, TiO 2 NS with rutile as the principal crystalline phase were prepared through the in-situ electrochemical oxidation of Ti 3 C 2 T x NS, offering a more accessible and sustainable alternative method compared to previously reported approaches. Density functional theory simulations demonstrated that electrochemical transformation method minimizes the phase transition energy difference and accelerates the phase transition. TiO 2 NS-based electrodes presented a low detection limit of 10.2 nM towards UA with sensitivity as 1.924 μA . cm –2. μM –1 (0.03–0.3 μM) and linear range from 0.03–0.3 and 0.03–300 μM, and achieved acceptable stability, interference resistance, temperature adaptability and feasibility in urine sample analysis. Our approach exhibits higher efficiency in inducing the anatase-to-rutile phase transition than the conventional method of high-temperature heating. Thus, our study elucidates the mechanism underlying the structural evolution and phase transition in TiO 2 NS from a thermodynamic perspective, offering valuable insights for the rational design of biosensing platforms towards biomolecules. TiO 2 nanosheets (NS) was in-situ fabricated and grown on the surface of Ti 3 C 2 T x NS controllably via the electrochemical oxidation of Ti 3 C 2 T x NS in the electrochemical reactor, as shown in Figure a. Extending the oxidation time leads to a monotonic increase in the surface coverage of TiO 2 nanoparticles (NP) until full coverage is achieved. Our synthesized TiO 2 NS exhibits superior electrochemical performance, owing to their increased surface-to-volume ration, shorter ion diffusivity paths, faster electron transferring and efficient immobilization of aptamers. Density functional theory simulations demonstrated that electrochemical transformation method minimizes the phase transition energy difference and accelerates the phase transition (Figure b). Our approach exhibits higher efficiency in inducing the anatase-to-rutile phase transition than the conventional method of high-temperature heating. Download: Download high-res image (252KB) Download: Download full-size image