This volume presents the fundamentals and advances in state-of-the-art catalytic nanoscale interventions to improve the efficiency of bioelectrochemical systems. These systems are used in a number of applications in the water-energy nexus. Contributed chapters describe and build on useful strategies to use and reference when dealing with an important environmental issue: the final disposal of heavy metal catalysts. Summarizing basic and translational research, these chapters are valuable for researchers in energy, nanotechnology, and catalysis.