Photoelectrochemical (PEC) water splitting to produce H₂ is a renewable method for addressing the worldwide energy consumption increasing and fossil fuels storage shrinking. In order to achieve sustainable PEC H₂ production, the semiconductor electrodes should have good photo-absorption ability, proper band positions and chemical stability in aqueous condition. Different from the large-band-gap semiconductors such as TiO₂ which can work efficiently under UV light, Si is an narrow-band-gap semiconductor that can efficiently absorb visible light; however, Si is indirect semiconductor and susceptible to photocorrosion in aqueous solution. In this paper, we demonstrate a new strategy of first protecting and then activating to develop a stable visible light photoanode for photoelectrochemical hydrogen production. This AgNPs/PEDOT/SiNW arrays show an encouraging solar-to-chemical energy conversion efficiency of 2.86% and a pronounced incident photo-to-current conversion efficiency (IPCE) across the whole visible region. Our strategy proposed here contributes to further improvement of corrosion protection and solar energy harvesting for narrow-band-gap semiconductors that employed in visible light photoelectrochemical and photoelectric conversion applications.

Schematic diagram of the hydrogen production PEC cell