Fig. 5: Wavelength effect and suggested mechanism of MIR light enhanced proton conductivity.

a Representation of passing wavelength ranges of the MIR narrowband bandpass filters A (brown shadow) and B (green shadow). The range for filter A is closest to the resonant frequency of O–H stretch vibration. b Wavelength effect of MIR light enhanced Δσ/σ of bulk and GB for filters A and B, and the control group. Schematic representations for the lattice vibration-assisted proton hopping process showing (c) excitation and relaxation of the O–H stretch vibration, (d) modulation of the potential energy surface (PES) of the proton due to subsequent excitation of the coupled lattice vibrations, and (e) proton transfer from the donor (O_I) to the acceptor (O_II). For reference, the dashed curve in (d) depicts the shape of the PES prior to resonant excitation, corresponding to configuration shown in c. The error bars in (b) incorporate standard deviations from three parallel measurements and fitting errors per sample across three samples prepared using the same method. Source data are provided in the Source Data file.