Bei Li

Antimony selenide (Sb₂Se₃) has emerged as a promising environmentally friendly photocathode material for photoelectrochemical (PEC) water splitting due to its suitable bandgap, high absorption coefficient, and anisotropic properties. In this study, Sb₂Se₃ thin films were prepared using a simple spin-coating method with precursor solutions of varying saturations. Raman spectroscopy characterization indicated that the 1.0 M Se-Sb precursor specifically formed well-defined [Sb₄Se₇]²⁻ selenoantimonate complexes. Further results from X-ray diffraction and high-resolution transmission electron microscopy confirmed that the resulting Sb₂Se₃ thin film exhibited higher crystallinity and a preferred orientation of (221)/(211) crystal planes. The FTO/NiOx/Sb₂Se₃/TiO₂/Pt photocathode fabricated based on this film achieved a photocurrent density of 25.9 mA·cm⁻² at 0 V vs. RHE and a half-cell solar-to-hydrogen conversion efficiency of 1.61%. Electrochemical impedance spectroscopy and open circuit potential measurements further demonstrated that the device prepared with the 1.0 mol/L precursor possessed superior charge separation and transport properties. This study reveals the critical role of optimizing precursor solution saturation in fabricating high-performance and low-cost Sb₂Se₃ photocathodes for solar hydrogen production.

Self-powered ultraviolet photodetectors with bipolar photoresponse have great potential in the fields of ultraviolet optical communication, all-optical controlled artificial synapses, high-resolution ultraviolet imaging equipment, and multiband photoelectric detection. However, the current low optoelectronic performance limits the development of such polar switching devices. Here, we construct a self-powered ultraviolet photodetector based on GaN and In/Sn-doped Ga₂O₃ (IGTO) nanowires (NWs) pn junction structure. This unique nanowire/thin film structure allows GaN and IGTO to dominate the absorption of light at different wavelengths, resulting in a highly bipolar photoresponse. The device has a responsivity of 2.04 A/W and a normalized detectivity of 7.18 × 10¹³ Jones at 254 nm and a responsivity of -2.09 A/W and a normalized detectivity of -7 × 10¹³ Jones at 365 nm, both at zero bias. In addition, it has an extremely high I_light/I_dark ratio of 1.05 × 10⁵ and ultrafast response times of 2.4/1.9 ms (at 254 nm) and 5.7/5.2 ms (at 365 nm). These excellent properties are attributed to the high specific surface area of the one-dimensional nanowire structure and the abundant voids generated by the nanowire network to enhance the absorption of light, and the p-n junction structure enables the rapid separation and transfer of photogenerated electron-hole pairs. Our findings provide a feasible strategy for high-performance wavelength-controlled polarity switching devices.