A novel
propitious nanoporous anodized stainless steel 316L (NASS316L)
photoanode was developed for water splitting. The anodization could
successfully produce a uniform nanoporous (∼ 90 nm in pore
diameter) array (∼ 2.0 μm thick) of NASS316L with a high
pore density. Several techniques, including FESEM, EDX, XRD, XPS,
ICP-OES, and UV–vis-NIR spectrophotometry, were employed to
characterize the catalyst and to assess and interpret its activity
toward water splitting. Surprisingly, the NASS316L retained almost
the same composition of the bare stainless steel 316L, which recommended
a symmetric dealloying mechanism during anodization. It also possessed
a narrow band gap energy (1.77 eV) and a unique photoelectrocatalytic
activity (∼ 4.1 mA cm–2 at 0.65 V versus
Ag/AgCl, 4-fold to that of α-Fe2O3) toward
water splitting. The onset potential (−0.85 V) in the photocurrent–voltage
curve of the NASS316L catalyst demonstrated a negative shift in its
Fermi level when compared to α-Fe2O3.
The high (23% at 0.2 V vs Ag/AgCl) incident-photon-to-current conversion
efficiency and the robust durability revealed from the in situ analysis
of the produced H2 gas continued recommending the peerless
inexpensive and abundant NASS316L catalyst for potential visible-induced
solar applications.