Evolutionary face-to-face 2D/2D bismuth-based heterojunction: The quest for sustainable photocatalytic applications

The energy demand is rising with the global population each day. The rapid growth in the manufacturing and energy industries has hit an unhealthy mark, losing control over the emission of harmful substances. Photocatalysis is considered to be one of the sustainable technologies for addressing the aforementioned problems. Two-dimensional (2D) bismuth-based nanomaterials have attracted extensive attention stemming from their visible light absorption ability. Nevertheless, pristine materials suffer from a high charge recombination rate. Heterojunction engineering has proven to effectively improve the separation efficiency of photogenerated charge carriers. Importantly, 2D bismuth-based materials have shown accelerated charge transfer mechanisms with the intimate face-to-face contact between nanostructures and a high adsorption rate as a result of the high surface-tovolume ratio that endows abundant active sites. Therefore, it is significant to elucidate the synergy effect between heterojunction and morphology engineering of bismuth-based photocatalysts. This review aims to discuss the progress of 2D/2D bismuth-based heterojunctions to provide critical insights into the fundamental reaction mechanism, synthesis of 2D bismuth photocatalyst, and advances of 2D/2D bismuth-based heterojunction photocatalysts in energy conversion and environmental remediation. Lastly, this review is anticipated to serve as a comprehensive work to evaluate the current challenges and future research direction of 2D/2D bismuth-based heterojunction photocatalysts.