Rational design of lead-free CsCu2I3@g-C3N4 composite for efficient energy storage and sustainable catalysis

Abstract

Rationally constructed lead-free halide perovskite-based composites provide an effective approach for upgrading their many unique physicochemical properties. In this study, we report the design and synthesis of a stable lead-free CsCu<inf>2</inf>I<inf>3</inf> (CCI) perovskite integrated with g-C<inf>3</inf>N<inf>4</inf> (CN) using a simple ultrasonication approach. The individual components, CsCu<inf>2</inf>I<inf>3</inf> and g-C<inf>3</inf>N<inf>4</inf>, were synthesized separately using the hot-injection method and the thermal polycondensation method, respectively. Interestingly, the composite material CsCu<inf>2</inf>I<inf>3</inf>@g-C<inf>3</inf>N<inf>4</inf> (CCI-CN) exhibited outstanding hybrid supercapacitive behaviour and opened a new avenue for the untapped electrochemical potential of Cu-based lead-free halide perovskites. The hybrid CCI-CN material was also examined, for the first time, as a heterogeneous multifunctional catalyst in the photo-hydration of benzonitrile and the photo-reduction of para-nitroaniline. Moreover, the synthesized composite catalyst was very efficient in the synthesis of the medicinally potent N-heterocyclic compounds, quinazolin-4(3H)-one moieties. It was observed that CsCu<inf>2</inf>I<inf>3</inf>@g-C<inf>3</inf>N<inf>4</inf> not only outperformed its individual components, CsCu<inf>2</inf>I<inf>3</inf> and g-C<inf>3</inf>N<inf>4</inf>, but also surpassed other reported catalysts in the aforementioned transformations, delivering excellent product yields. This was attributed to the cooperative and synergistic effects of the CsCu<inf>2</inf>I<inf>3</inf> and g-C<inf>3</inf>N<inf>4</inf> heterojunction. Photoluminescence studies revealed that the reduced recombination in the composite material provided a fast channel for the transfer of photo-generated electrons, with the lower PL lifetime of CCI-CN (119.8307 ns) compared to CCI (151.2798 ns). Hence, this study provides ideas and opportunities of Cu-based halide perovskite composites as efficient materials for charge storage and versatile catalytic activity. © 2025 Elsevier B.V., All rights reserved.