Bipolar membranes have been studied for >50 years for application in electrodialysis at moderate current densities (<100 mA/cm²). In the past decade bipolar membranes have experienced a renaissance due to interest in driving higher current density processes with intentional pH gradients between the anode and cathode, such as CO₂/H₂O electrolysis and electrochemical generation of acid and base for direct oceanic carbon capture, two applications that my group actively studies. My group’s main contribution to this field is that we recently showed that bipolar membranes are in fact high-quality protonic diodes, where water serves as a (protonic) semiconductor. Using Mott–Schottky analysis and Butler–Volmer analysis, we reported on the performance of said materials. Using this platform, we have demonstrated photovoltaic action from photoacid-dye-sensitized bipolar membranes. More recently, we have studied how intentional placement of proton-donating and proton-accepting groups in the space–charge region forms a recombination/generation junction, which are the non-tunneling variants of tunnel junctions that are important in tandem solar cells. This allows for rapid protonic conduction across originally rather insulating junctions, as desired for ionic conductors in most electrochemical devices. Collectively, our efforts form the foundational framework for new functions and resulting applications that benefit from protonic transfer and transport.