The heterostructured n-Si/SiO x /TiO x /NiFe oxyhydroxides-alloy photoanode exhibits a low onset potential of 1.06 V vs. reversible hydrogen electrode (RHE) at 10 mA cm -2 , an accelerated kinetic process with a Tafel slope of 34.9 mV/dec, and high saturated current density of 38.4 mA cm under one sun illumination in 1 M KOH, providing a record ABPE value of 4.24%. The catalyticprotective oxyhydroxides-alloy layer extends the device lifetime beyond 250 h at a current density higher than 30 mA cm -2 , retaining nearly 88% of the initial current density.