Layered Porous Graphitic Carbon Nitride Stabilized Effective Co 2 SnO 4 Inverse Spinel as a Bifunctional Electrocatalyst for Overall Water Splitting.

Developing an efficient, low-cost, and non-noble metal oxide-based nanohybrid material for overall water splitting is a highly desirable approach to promote clean energy harnessing and to minimize environmental issues. Accordingly, we proposed an interfacial engineering approach to construct layered porous graphitic carbon nitride (g-C 3 N 4 )-stabilized Co 2 SnO 4 inverse spinel nanohybrid materials as highly active bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. Here, a Co 2 SnO 4 /g-C 3 N 4 nanohybrid with a layered porous g-C 3 N 4 stabilized cubelike inverse spinel has been synthesized with an enhanced surface area via a simple one-pot hydrothermal method. Besides, detailed structural and morphological characterizations were carried out using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR), and Brunauer-Emmett-Teller (BET) analysis. Briefly, XPS analysis has revealed the existence of a strong coupling bond at the interface between a definite proportion of g-C 3 N 4 nanosheets and the inverse spinel, which act as an electron transport channel to explore the exceptional performances for HER and OER. Compared to the Co 2 SnO 4 inverse spinel lattice or g-C 3 N 4 nanosheets, the prepared Co 2 SnO 4 /g-C 3 N 4 nanohybrid-loaded 316 SSL mesh electrode showed excellent and stable electrocatalytic performances with very low overpotentials of 41 mV for HER and 260 mV for OER to reach the current density of 10 mA cm -2 . To understand the electrocatalytic phenomena, the faradic efficiency was calculated for the prepared bifunctional electrocatalyst as 96%, which effectively would favor water electrolysis. Accordingly, the Co 2 SnO 4 /g-C 3 N 4 nanohybrid-loaded electrodes were constructed, and the minimum cell voltage was found to be 1.52 V to reach the current density of 10 mA cm -2 , which is comparable to the standard RuO 2 ∥Pt/C in two-electrode systems. Thus, the developed nanohybrid-based electrocatalyst could be an alternative to noble metal-centered systems for highly efficient overall water splitting.