High-Efficient Water Splitting Using Nanostructured Conical GaN

Abstract

Nanostructured GaN has many advantages in water splitting, such as stronger light absorption, shorter migration distance and more reactive sites. Here, we have introduced a conical nanostructured GaN with the significant improvement of water splitting performance. The fabrication method is simple without any extra mask, including electrochemical etching and ICP etching only, which largely reduces the complexity and cost for fabricating nanostructured GaN. By making use of the large number of pores formed in electrochemical etching, a conical GaN nanostructure can be prepared using ICP etching afterwards. Compared with the control planar GaN, the reflectivity of the conical GaN decreases by ∼2.57 times, indicating the light absorption of the conical GaN increases significantly. The corresponding water splitting current density of the conical GaN has also been measured, which is 0.69 mA cm−2 at 1 V, ∼6.27 times higher than that of control planar GaN (0.11 mA cm−2). Our work provides a simple method to fabricate high-performance nanostructured GaN, and broadens the application of III-nitrides for efficient energy storage and conversion.