A research team at the Institute for Solar Fuels at HZB has made significant strides in increasing hydrogen production efficiency through the use of pressure in photoelectrochemical cells (PEC cells). These cells mimic the natural process of photosynthesis by using artificial photoelectrodes to split water into hydrogen and oxygen under sunlight. The team discovered that operating PEC cells at elevated pressures, between 1 and 10 bar, can lead to a substantial increase in efficiency. By pressurising the PEC flow cells, the team observed a reduction in energy losses due to bubble formation, resulting in a potential 5-10% relative increase in overall efficiency. The study, published in Nature Communications, highlighted that at 8 bar pressure, energy losses could be halved, and optical scattering losses almost completely avoided. Dr. Feng Liang, the first author of the paper, emphasized the importance of operating pressure in affecting gas bubble size and behavior at the electrodes. Prof. Dr. Roel van de Krol, the head of the Institute for Solar Fuels, noted that the findings, including the developed multiphysics model, can be applied to enhance the efficiencies of various electrochemical and photocatalytic devices. The team recommended an optimum operating pressure range of 6-8 bar for PEC electrolysers, indicating that this approach could significantly improve hydrogen production processes in the future.