Heat-assisted hot-hole transfer increases the surface-enhanced Raman activity of Au-TiO₂ nanoarrays

Monitoring the evolution of molecules during photo and thermal synergistically induced physical and chemical processes is of paramount interest in fields including chemical, material, and energy research. Surface-enhanced Raman spectroscopy (SERS) is a highly promising technology in this regard, offering advantages of sensitivity, real-time, and label-free detection. However, the application of conventional SERS in high-temperature environments has faced challenges due to the inevitable loss of activity and decline in sensitivity. Herein, we synthesize Au-TiO₂ nanoarrays as SERS substrates, and an anomalous enhancement of Raman signal with increasing temperature is observed. The signal intensity increases by 11.41 times at 180 °C compared to that at 22 °C. This high-temperature enhancement in Raman activity is attributed to an underlying mechanism: heat-assisted hot-hole transfer, which enables 785 nm photon-induced hot-hole transfer from Au to TiO₂. Our work expands the application of the SERS technique for high-temperature chemical analysis and molecular diagnostics.