A review on dimensionally controlled synthesis of g-C3N4 and formation of an isotype heterojunction for photocatalytic hydrogen evolution

Abstract

To prevail over the challenges of high density defects at the interface and unfavourable compatibility among two anisotype semiconductors, rational design of an isotype heterojunction has emerged as an alternative effective strategy. Construction of an isotype heterojunction having similar structural parameters at the nanoscale level and well matched band structures was found to enhance the photocatalytic performance of the photocatalyst by promoting the charge separation. Particularly, the well-matched band structures in an isotype heterojunction designed by dimensional variation result in the formation of a high performance material for photocatalytic applications. To start with, we have discussed the synthesis processes and characterization of various isotype heterojunction systems giving emphasis on g-C₃N₄-based systems and classified all the systems as 0D–2D, 1D–2D and 2D–2D. Keeping in mind the ease of designing through a facile co-condensation method, cost-effectiveness, and environment friendly approach, we have summarized the design strategies and interface chemistry in such heterojunctions towards efficient photocatalytic hydrogen generation. The charge transfer mechanism in different morphologically and dimensionally controlled isotype heterostructures such as point-to-face (0D/2D), line-to-face (1D/2D) and face-to-face (2D/2D) was systematically discussed with suitable examples. We believe that this comprehensive timely review will promote further developments in this area of research providing stimulating perspectives in future for the construction of multidimensional isotype heterostructures towards sustainable energy development.