Abstract

Photocatalysis has emerged as a crucial technology for utilizing solar energy to combat global warming and energy shortages. In this realm, both organic and inorganic halide/oxide perovskites have attracted considerable interest. Despite the prevalence of research on lead-based perovskites, the focus is shifting towards lead-free alternatives due to lead's detrimental environmental impact. These materials are at the forefront of developments in photovoltaics, optoelectronics, and photocatalysis. When combined with carbon-based materials to form heterojunctions, lead-free perovskites demonstrate outstanding photocatalytic performance while being cost-effective. This review examines various synthesis methods for lead-free perovskites and their numerous heterojunctions with carbon-based materials. It specifically highlights Z- and S-scheduled heterojunctions, emphasizing their use in hydrogen production, carbon dioxide reduction, and oxygen evolution. The review emphasizes the evolving field of scientific research aimed at solving current energy and environmental issues. © 2025 The Royal Society of Chemistry.