Composite of Nickel Oxide Hexagonal Sheet Supported on Carbon Nitride for Photo-Electrochemical Water Splitting

Abstract

Developing highly efficient and cost-effective electro-catalysts for the photo-electrochemical (PEC) water splitting is of great significance, since its two reactions, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is coupled with the key clean energy systems. However, the prohibitive costs and scarcity of precious metals used as OER and HER catalysts (e.g. IrO2, RuO2, Pt) limits the large scale commercialization. Herein, we report a facile and cheap novel organic-inorganic hetero-structured electro-catalyst: 2D nickel oxide (NiO) hexagonal sheet supported on graphitic-carbon nitride (g-C3N4) which has been successfully synthesized using in-situ solid-state heat treatment. The Transmission electron microscopy (TEM) characterization confirms that NiO are homogeneously dispersed on the surface of g-C3N4. The presented catalyst display outstanding activity in catalyzing PEC water splitting with a potential of 130 mV for OER and 5 mV for HER for the reaction to start. Moreover, the maximum current density obtained at an overpotential of 200 mV are 20 mAcm-2 and 1000 mAcm-2 for OER and HER, respectively. Our findings reveal that the rational interaction between two-dimensional materials can remarkably promote the hydrogen and oxygen production reactions, thus boosting the entire clean energy system. Furthermore, our work also reveals the importance of local transition metal coordination in catalysts for the OER and HER which would lead to new class of low-cost, durable and efficient water splitting catalysts. Figure 1