Layered Trichalcogenidophosphate: A New Catalyst Family for Water Splitting

With the rapidly increasing demand for energy and extensive use of fossil fuels, there is an urgent need to find alternative sources of clean energy to solve the ever-growing environmental problems. Hydrogen, the simplest and most abundant element in the universe, has a high energy density and is sustainable and eco-friendly. The combustion of hydrogen with air/oxygen offers high energy and gives off water as the end product. Hence, hydrogen is considered one of the most promising candidates for fulfilling future energy demands [ 1 , 2 ]. It has been long recognized that water can be decomposed under solar excitation in plants. Electrical power can also be used to facilitate water splitting into gaseous hydrogen and oxygen, which can be stored for further use. However, it is still a huge challenge to split water on the industrial scale as efficiently as in plants. Moreover, the state-of-the-art electrocatalytic techniques for water splitting still rely heavily on noble metal catalysts such as Pt for the hydrogen evolution reaction (HER) and IrO 2 for the oxygen evolution reaction (OER). Thus, the generation of hydrogen and oxygen is a high-cost operation, making the use of hydrogen and oxygen as commercial fuels challenging. Therefore, it is highly desirable to find earth-abundant, cost-effective, and highly active catalysts for water splitting [ 3 ].