Ultra-thin g-C3N4 nanosheets wrapped silicon nanowire array for improved chemical stability and enhanced photoresponse

• g-C3N4, as an oxygen free and metal free protective material for Si, was proposed.
• g-C3N4 nanosheets wrapped Si nanowire array was synthesized.
• SiNW/g-C3N4 exhibited enhancement of photoelectrochemical stability and photocurrent.

In order to inhibit the oxidation of Si materials in aqueous solution, Si nanowire array was wrapped by ultra-thin g-C3N4 nanosheets via an electrophoresis process. Scanning electron microscopy and transmission electron microscopy images showed that g-C3N4 nanosheets were evenly distributed on the surface of Si nanowire array. X-ray diffraction patterns indicated that Si nanowire array/g-C3N4 nanosheets were composed of Si (4 0 0 crystal plane) and g-C3N4 (0 0 2 and 1 0 0 crystal planes). The cyclic voltammetry curves revealed that the corrosion of Si nanowire array was restrained under the protection of g-C3N4 nanosheets. Furthermore, the photocurrent density of Si nanowire array/g-C3N4 nanosheets increased by nearly 3 times compared to that of bare Si nanowire array due to the effective charge separation caused by the built-in electric field at the interface. This work will facilitate the applications of Si materials in aqueous solution, such as solar energy harvest and photocatalytic pollution control.

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