Enhanced photoresponse in Au-decorated MoSe2 photoanodes for dual-wavelength photoelectrochemical applications

By utilizing photovoltage competition between two photoelectrodes, we have successfully fabricated a photoelectrochemical (PEC) device that features switchable photocurrent polarity for wavelength-selective photodetection. Composed of distinct semiconductor materials, this device exhibits a negative photocurrent density of −1.98 μA/cm 2 under 365 nm illumination and a positive photocurrent density of 0.46 μA/cm 2 under 650 nm illumination, without requiring an external power source. The observed bidirectional photocurrent is attributed to the photovoltage competition mechanism between the photoelectrodes. Notably, the photocurrent and responsivity under 650 nm illumination are significantly enhanced following the deposition of Au nanoparticles on the MoSe 2 photoelectrode. In a three-electrode system without ZnO electrodes, the photoresponse is increased by three orders of magnitude after Au nanoparticle modification. Similarly, in a two-electrode system with ZnO electrodes, the photoresponse is enhanced by more than fifty times following Au modification. This enhancement promotes more efficient redox reactions within the device, thereby offering a novel strategy for wavelength-selective photodetection. This innovation has substantial application potential in the field of photoelectrochemistry.