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Conducting polymers (CPs) have been proved to be instrumental in enhancing photocatalytic efficacy owing to their unique physicochemical properties and energy levels. In this regard, titanium dioxide (TiO2) has been investigated in transdisciplinary research areas (like catalysis, energy technologies, health, and environment) due to its desirable characteristics. In the process of developing advanced photocatalysts, novel inorganic–organic heterojunction design based materials have been explored and developed in contrast to conventional, inorganic–inorganic type semiconducting photocatalysts (SCPs). In this context, hybrid/composite SCPs comprising CPs and TiO2, have received significant attention for enhancing photocatalytic efficacy in terms of activity as well as visible light activation. The synergistic contribution from CPs (here we focus only on polyaniline (PANI) and polypyrrole (PPy)) and TiO2 have been proved to enhance light-absorption capability in the visible region, photogenerated extraction, and higher stability. Importantly, the published literature (before 2015) on the photocatalysis of TiO2-CP composites mainly discusses in terms of the sensitizing aspects of CP for TiO2. However, there is a critical need to review the literature (beyond 2015) to explore the state of art progress concerning the mechanism of photocatalytic performances as phenomenal parallel developments and knowledge gaps have been addressed on new kinds of heterojunction formation (like S-Scheme over traditional ones), band tuning and interfacial contact effects between two SCPs. In particular, this topical review aims to capture and highlight the current advancements (2016–2021) in relevance to the visible light photocatalytic performance of CP–TiO2 functional composites, which include nanostructures and multi-components. The predominantly available literature over the last five years on the application of CPs–TiO2 functional composites for monitoring or removal of pollutants under visible light activation is reviewed giving importance to revealing the role of CP in concurrent enhancement in both visible light activation and photocatalytic performances. Finally, we elaborate on the challenges and future outlook for advanced research and development in this area.

Health monitoring, e-skin, and soft robotics call for large-area and robust energy-harvesting strategy to powering their embedded sensors and peripheral electronics. Triboelectric nanogenerator (TENG) is an optimum option to energizing self-powered sensors and self-charging systems. Herein, a large-scale facile and compatible bar-assisted printing method is presented to achieve hierarchically microstructured polymer composite triboelectric film with good hydrophobicity to improve the electrical output performance and achieve the robustness of TENG. The electrical outputs of the TENG devices are tuned by imparting the graphite fillers into polydimethylsiloxane (PDMS) with optimal concentration. The achieved microstructured graphite/PDMS composite based TENG supplies high and stable short-circuit current of 42 µA, open-circuit voltage of 410 V, and transferred charges of 160 nC under an applied force of 1.2 N, which are sufficient enough to power wearable sensors or charge the energy storage devices. The TENG devices can charge a 2.2 µf capacitor to 1.5 V within 2 s, lighten 30 commercial green LEDs, and drive an electronic watch as well. Self-powered tactile sensing has also been demonstrated by attaching the TENG devices onto a rubber glove to monitor the process in grasping objects. Furthermore, a large-scale self-powered sensor array is fabricated and utilized to map the spatial pressure distributions. This work not only demonstrates a scalable fabrication of the hierarchically microstructured polymer composite films for high-performance TENGs with high electrical outputs, excellent durability and ambient stability, but also brings insight into the development of future cost-effective and self-powered electronics.