Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

Abstract

Here, we develop a series of hybrid Ag@g-C3N4/r-GO nanocomposite materials that are highly active, durable, and adaptable for electro- and photocatalytic H2 generation under visible light by employing a rapid and simple sonochemical technique. Multiple catalytic behaviors can be achieved through the strategic introduction of Ag metal into a hierarchical structure consisting of photo- and electroactive two-dimensional (2D) sheets with various band configurations. The outcomes of this work show the development of heterojunctions and show how electro- and photocatalysis were both synergistically improved. The fabricated materials were examined for photocatalytic hydrogen evolution, photoelectrocatalytic (PEC) hydrogen evolution, and electrocatalytic hydrogen evolution reaction (HER). In both photocatalytic conditions at 1.5 AM simulated light irradiation and electrocatalytic conditions, silver-doped composites showed better activity. Among all of the fabricated catalysts, the Ag20%@g-C3N4/r-GO (A20CNG) catalyst displayed the highest apparent quantum yield (AQY) of 1.69 and the highest hydrogen generation rate (954 μmol g–1 h–1). However, in the case of electrocatalysis, Ag15%@g-C3N4/r-GO (A15CNG) showed impressive HER activity with a low overpotential (η) of 0.484 V at 10 mA cm–2 current density with 130.6 mV dec–1 Tafel slope value and also exhibited approximately 16 times more current density than that of g-C3N4/GO (CNGO) at a fixed overpotential in the HER process; this was also supported by the electrochemical active surface area (ECSA). On the basis of the impressive results shown above, the Ag@g-C3N4/r-GO (ACNG) catalyst might be a promising and flexible nanocomposite for photo-, photoelectro-, and electrocatalytic hydrogen evolutions. This is the first study to our knowledge that provides the results of a comprehensive examination into the photo- and electrocatalytic application of an interesting and versatile bifunctional catalyst.