Multifunctional Nickel Sulfide Nanosheet Arrays for Solar-Intensified Oxygen Evolution Reaction

Electrochemical water splitting for hydrogen production is currently hindered by the sluggish kinetic of anodic oxygen evolution reaction (OER). By integrating photothermal materials into electrocatalytic network and thus allowing solar energy to work as additional driving force, the OER is expected to be boosted. However, the rational design of such electrochemical system still remains a challenge due to the spatial inconsistency between photothermal component and electrocatalytic component. Herein, it is reported that multifunctional nickel sulfide (Ni₃ S₂ ) nanosheet arrays show both photothermal and electrocatalytic properties for solar-intensified electrocatalytic system, which well eliminates the spatial inconsistency between the aforementioned two types of functional components by using one bifunctional material. The deliberate design of nanoarray architecture formed by the interconnected Ni₃ S₂ nanosheets endows larger surface area and higher surface roughness, thus enhancing light absorption by suppressing diffuse reflection and facilitating electron transfer in electrocatalytic reactions. Therefore, the OER activity is significantly improved. Under light illumination, the current density of Ni₃ S₂ nanosheets could reach 492.2 mA cm^-2 at 1.55 V, about 2.5-fold that in dark conditions, with a Tafel slope of as low as 60 dec^-1 . The solar-intensified electrochemical system based on multifunctional material presents prospective potential in electrochemical water splitting for efficient hydrogen production.