Performance Efficiency of PEM Electrolyzer Stacks with Nano-Coated Titanium PTLS and Bipolar Plates

Abstract The study presents an industrial-scale evaluation of two PEM electrolyser stacks incorporating Naco-engineered titanium coatings on porous transport layers (PTLs) and bipolar plates. Stack 0316/44 included both coated PTLs and coated bipolar plates, while Stack 0317/44 utilised only coated PTLs. Both stacks were conditioned for 40 hours at 15 bar and subsequently tested at current densities of 0.6 and 1.2 A cm −2 . At 150 A, the total voltages measured were 89.8 V for 0316/44 and 88.9 V for 0317/44, whereas at 300 A, they reached 99.3 V and 102.8 V, respectively. Gas purity remained within safe limits, with residual oxygen (O 2 ) in hydrogen (H 2 ) ranging from 14 ppm to 31 ppm and H 2 crossover remaining below 0.7 % across all tests. Integrated operation in the SIRIO 1000 system at 300 A produced the combined voltages of 106.0 V and 104.0 V for the two stacks. Average power consumption during joint operation was 5.75 kW/Nm³, approximately 10–20 % higher than that of standard industrial stacks. The results confirm the stable operation and acceptable gas-separation performance of the coated components under high-pressure, high-current conditions, while also identifying efficiency gaps that require further optimisation. The study provides the first comparative industrial assessment of the coated PEM stack architectures and establishes a foundation for future durability and optimisation studies.