Facile fabrication of a metal-free 2D–2D Nb2CTx@g-C3N4 MXene-based Schottky-heterojunction with the potential application in photocatalytic processes

Clean energy production and environmental detoxification through photocatalysis have received widespread attention due to their efficiency and capability to address global energy and environmental related calamities. Moreover, graphitic carbon nitride (g-C3N4) and many other single-semiconductor based photocatalysts have been widely explored; however, their performance is still unsatisfactory. Herein, the engineering of g-C3N4 as a primary photocatalyst interlayered with niobium carbide (Nb2CTx) MXene co-catalyst for the formation of efficient photo-responsive Schottky-heterojunction photocatalyst is demonstrated. Visible-light absorption of g-C3N4 is proportional to the Nb2CTx contents. Moreover, g-C3N4 energy bandgap was significantly lowered from 2.61 eV to 2.19, 2.08, and 2.32 eV for 1, 3, and 5 wt% of Nb2CTx loaded onto g-C3N4, respectively. Nb2CTx MXene as a co-catalyst allows a formation of an efficient photocatalyst with high potential to eliminate the use of costly noble metals. The devised Schottky-junction restrained the electron recombination rates threefold relative to the pristine g-C3N4. The conduction band potential of g-C3N4 and the composites were observed to be more positive in relation to the standard reduction potential of O2/•O2- (−0.33 V) CO2/CO (−0.53 V), CO2/CH4 (−0.24 V), H2/H+ (0.0 V), signifying its merits potentials for photocatalysis. The observed charge carriers with more negative reduction potential facilitates efficient photocatalytic reactions, particularly in hydrogen production and catalytic transformation of carbon dioxide into useful sources of energy. Fabricating a heterostructure between g-C3N4 and Nb2CTx MXene demonstrates the feasibility of facile preparation of photocatalysts with merit features due to synergistic catalytic effects.