Large-area ordered P-type Si nanohole arrays as photocathode for highly efficient hydrogen production by photoelectrochemical water splitting

Abstract

Large-area highly ordered P-type silicon nanohole (SiNH) arrays have been fabricated by the combination of metal assisted electroless etching and nanospheres lithography technique, and systematic investigations of photoelectrochemical hydrogen evolution behavior of SiNH arrays were also reported in this study. The SiNH arrays exhibited a maximum limiting photocurrent density of 28 mA cm−2, higher than that of SiNW arrays (24 mA cm−2) and the planar Si (21.5 mA cm−2). The improved performance was attributed to SiNH arrays providing a patterned and ordered nanoholes structure as a result of enhancement of the light harvesting as well as charge transportation and collection efficiency. Furthermore, we have demonstrated that the photoelectrode consisting of longer SiNH yielded a higher limiting current. However, when the length of SiNH was increased further, the limiting current dramatically reduced, which is due to an increased interface recombination and scattering resulting from the increased surface area of SiNH begin to play a dominant role. The relationship between the diameter of nanoholes and the photoconversion efficiency of SiNH arrays was also discussed. By implementing this ordered SiNH arrays into electrode design, one may be able to advantageously impact PEC and photovoltaic device performance.