## 1 Introduction
In the anode, exoelectrogenic microorganisms donate electrons to the electrode, acting as anodic biocatalysts to anaerobically oxidize the organic substrates. In the cathode, heterotrophic microorganisms use free electrons to achieve CO\({}_{2}\)/HCO\({}_{3}\) reduction with the generation of value-added products. The study of BESs started in 1911, when [PERSON] came to the conclusion that it was possible to release electrical energy from the decomposition of biodegradable substrates by microbial cultures [31]. The research history of BESs is characterized by its discontinuity. BESs gained relevance in the 1960s when researchers from the National Aeronautics Space Administration (NASA) space program considered the technology to obtain electricity from organic wastes in spaceships; however, other emerging technologies such as photovoltaic energy eclipsed the interest in BESs [32]. Between the 1980s and 2000s, some research works were published (on average, three publications per year) focused on the study of BESs and MFCs; however, it was only in the 2000s that research on this technology emerged, going from around 10 publications per year in 2000 to more than 1500 in 2024. The exponential growth in publications observed since 2005 has helped facilitate the increase in the power density significantly (1-1000 mW m\({}^{-2}\)) by means of electrode material modifications, microbial culture selection, metabolic mechanism understanding and cell architecture design; however, there are still challenges before full-scale implementation of the technology can be carried out for industrial or commercial application of BESs [29; 33]. Unfortunately, the use of photosynthetic microorganisms or microalgae as biocatalysts in MFCs, usually called Microalgae Microbial Fuel Cells (mMFCs), is more recent as can be seen in Figure 2. During the last years, the number of publications in the topic mMFC reached around 40 per year, a value significantly lower than those obtained by conventional MFCs based on other cathodic catalysts. Among BESs, MFCs are devices capturing great interest because of their applications in wastewater treatment, versatility and wide-ranging applications and studies. Additionally, the coupling of microalgae in MFCs could present several advantages that make mMFCs an interesting option. In this context, the present review offers a comprehensive analysis of the current state and future prospects of the mMFCs. Following the introductory section, the broader landscape of BES configurations will be contextualized. The review then delves into the core of mMFCs, detailing key aspects such as the fundamental role of microalgae, their integration with MFC technology, and the critical influence of environmental factors like  
Figure 2: History of publications related to MFC, BES and mMFC (Database: Scopus). light, CO\({}_{2}\), and trace minerals on mMFC performance. The main components, operational mechanisms, and behaviors of mMFCs are also examined in light of factors affecting them, including operational variables, design variables, and electrochemical characteristics, to enhance the mMFC efficiency. Additionally, the review discusses the most relevant research topics, including system configurations, materials, electron transfer mechanisms, and scale-up considerations. Looking towards the future, the review addresses improvements in geometry, electrodes, membranes, pH, harvesting techniques, strain selection, and the importance of modeling and metabolic research. This comprehensive analysis highlights the potential applications of mMFC systems in electricity generation, wastewater treatment, and CO\({}_{2}\) capture, addressing critical global challenges. Furthermore, the manuscript explores the integration of mMFCs with ecological and industrial systems, proposing pathways for practical deployment. This work outlines strategies to enhance their efficiency, providing a solid foundation for future research and technological advancement.