Design of Stable 2D Heterostructured Photocatalyst for Drastically Improved Hydrogen Generation and Unravelling the Underlying Charge Carrier Dynamics

Abstract

AbstractThe design of heterostructured photocatalysts comprising of 2‐D mesoporous C3N3 (π‐conjugated bonds with one less nitrogen atom in the ring to promote the better electron transport unlike conventional g‐C3N4) donor coupled with the MoS2 acceptor by a template‐directed thermal synthesis followed by hydrothermal synthesis is presented. The formation and coupling of MoS2 through basal planes on the surface of mpg‐CN has been confirmed by the XRD, XPS (C/N ratio of the order of 1), and lengthening of the C−N bond as revealed by increasing intensity of FTIR peak (1232 cm−1), respectively. Upon optimization, MS‐mpg‐CN exhibits 10‐fold enhancement in hydrogen generation rate and efficiency (∼86500 μmolg−1 h−1, IPCE: ∼64 %) than that of observed for MS‐mpg‐C3N4 photocatalyst (∼8250 μmolg−1 h−1, IPCE: ∼5.6 %). The lower PL emission intensity, average lifetime (1.91 ns) of charge carriers, precise semicircle in Nyquist plot and higher degree of band bending (Efb −0.64 eV), higher ‘g’ value (2.0038) in the EPR imply improved charge carrier separation, transfer kinetics and formation of intimate heterojunction, respectively. Furthermore, hydrogen evolution measured for subsequent days while reusing photocatalyst shows no significant change in the activity (∼1.2 % variation over three consecutive cycles), confirming their photostability and reusability.