Bifunctional materials possess remarkable properties that allow them to store and convert electrical energy easily. In this paper, diatomite-like potassium iron disulfide (KFeS2) was synthesized by a multistep sacrificial template method, and its morphological, electrochemical, and oxygen evolution reaction (OER) properties were investigated. KFeS2 was found to be porous, hollow, and cake-like, which suggests a high specific surface area (SSA) and abundant electrochemically active sites. A very high specific capacitance of 651 F g−1 at 1.0 A g−1 was also obtained due to the substance’s unique structure and high porosity. Additionally, the diatomite-like KFeS2 possessed a very low overpotential ƞ10 of 254 mV at a current density of 10 mA cm−2 and a small Tafel slope of about 48.4 mV dec−1. Thus, the diatomite-like KFeS2 demonstrates broad application prospects for both energy storage and conversion.
