Abstract
Despite the natural cycle of climate change being unavoidable and the reality, history has been telling the living the previous civilizations that have overstressed themselves or pushed the consumption of natural resources to the limit, and the consequence soon shows the alert in the climate. It is a critical period of time to change the current in response to climate change by employing environmentally friendly and emission-free energy technologies. The applications of advanced functional thin films ranging from the quantum level to nano and microscale, from inorganic metal oxides to conductive polymers, have been pushing the rapid development of energy-saving technologies and clean and renewable energy production, storage, and conversion in the past decade. This specific chapter focuses on fundamental- and applied- science on various advanced thin films and their applications in reliable renewable energy devices and/or systems, including but not limited to electrochromics, supercapacitors, fuel cells, flow batteries, electrolysis, triboelectricity, etc. Given that much of the work is realized across interfaces, the spotlight is shielded onto the interface of thin films in electrochemistry with different emerging cutting-edge ongoing research examples.