Enhancing the water splitting performance via decorating Fe2O3 nanoarrays with oxygen-vacancy-rich Ni1-xFexS electrocatalyst

In this work, oxygen-vacancy-rich Ni1-xFexS electrocatalyst modified Fe2O3 nanoarrays photoanode (denoted as Ni1-xFexS/Fe2O3) has been prepared firstly through a facile dripping solution method and a sulfurized process. As-prepared Ni1-xFexS/Fe2O3 anode shows a very high photocurrent density of ∼3.48 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE) and a saturated photocurrent density of 7.03 mA/cm2 at 1.57 V vs. RHE in PEC water splitting, which is 2.5 times of Fe2O3 (1.38 mA/cm2 at 1.23 V vs. RHE and 2.98 mA/cm2 at 1.57 V vs. RHE, respectively). Moreover, the photocurrent onset potential shows a distinct negative shift of about 272 mV. The Ni1-xFexS/Fe2O3 photoanode is controllable to achieve superior PEC performance because of the synergistic effects of Ni1-xFexS electrocatalyst and oxygen vacancies. Since in situ formed Ni1-xFexS electrocatalyst not only increase electrochemical active surface area of electrode, but also dramatically decrease solid and electrolyte interface resistance as well as dramatically suppresses charge carrier recombination in Fe2O3 photoanodes. In the meanwhile, introduced the oxygen vacancies in a sulfurized process of Ni1-xFexS electrocatalyst serve as active sites for sufficient chemical reaction. Hence, our work testifies oxygen-vacancy-rich Ni1-xFexS not only act as a promising OER electrocatalyst, but also offers a new strategy to prepare efficient and low-cost PEC solar energy conversion devices.