In Situ Degradation and Fast Online Detection via 3D Gold Nanodendrite Hybrids as a Photoelectrode and SERS Substrate

Plasmonic metal-support composites have been explored for heterogeneous catalysis with poor robustness under in situ conditions. The substrate performance index for surface-enhanced Raman scattering (SERS) is also limited by spatial heterogeneity and signal instability. Most reported hybrid devices still face a clear trade-off between catalytic and SERS performance, and durable multifunctionality in one integrated system remains largely unexplored. This study reports an integrated platform that combines photoelectrode, photocatalytic, and SERS functions, delivering stable photocurrent, high catalytic efficiency, and reproducible Raman activity, respectively. Herein, a systematic sputtering/electrodeposition combined with a single-step, temperature-controlled annealing route yields hybrid titanium dioxide (TiO₂)/gold (Au) nanodendrites. The interconnected Au-TiO₂-H₂O interfaces promote efficient separation and interfacial transport of photogenerated charge carriers, while interdendritic junctions and sharp tips localize target molecules with high-|E|⁴ SERS hot spots. The composite enabled on-site detection of malachite green (MG⁺) in aquaculture water followed by in situ photoelectrocatalytic degradation, administering complete removal (C_t/C₀→0) for feed concentrations up to × 10^-4 mol/L in a 60 min interval, with synchronous real-time, online monitoring of MG⁺ across the entire degradation period. The composite also generated a stable and high photocurrent response at -0.73 V to serve for photoelectrochemical applications as a photoanode. Finally, the storage stability, reproducibility across synthesis batches and uniformity (RSD of 10.998% at n = 100), reusability for at least six cycles, self-cleaning, and repeatable detection performance demonstrate that this integrated sensing-degradation platform offers potential for deployment in operational aquatic matrices.