Response behaviour of proton exchange membrane water electrolysis to hydrogen production under dynamic conditions

Hydrogen production via proton exchange membrane water electrolysis (PEMWE) coupled with renewable energy sources is gaining considerable attention due to its high current densities and flexible responses. This study investigated the voltage responses of PEMWE under dynamic conditions. Three comprehensive performance parameters were adopted to determine the response behaviours of PEMWE devices, including the total response time (TRT), the voltage stability (Vmax - Vmin), and the difference between the voltages seen for dynamic and static conditions (ΔV = Vdynamic - Vstatic). The obtained results showed that with small step currents (ΔI = 1 A) and low currents (I < 9 A), PEMWE presented better responses. The TRT was less than 30 s, (Vmax - Vmin) was less than 10 mV, and ΔV was less than 20 mV. Increasing the amplitude of the step current increased the response time and reduced the voltage stability during electrolysis. The Joule heat produced by the inner resistance have been responsible for the different response behaviours of the PEMWE devices. A durability test showed that after a square wave operated for 300 h, significant degradation of the PEMWE response was observed by comparing the voltage response parameters. Electrochemical characterization studies indicated increases in the static voltage, resistance, and Tafel slope, which were consistent with the degradation of the PEMWE response.