Superimposed pulse-controlled electrolysis for optimal hydrogen evolution using Mn/MnSO4 redox pair

An effective power input is essential for achieving high-performance electrolysis in water splitting, characterised by a high hydrogen production rate and low energy consumption. This study investigates the optimisation of electrochemical performance in a novel hybrid manganese cycle by employing a superimposed pulsation technique to enhance hydrogen generation and realise “Power-to-Manganese-to-Gas”. The electrolysis system was comprised of a proton exchange membrane (PEM) incorporated with the Mn/MnSO 4 redox pair to facilitate efficient water splitting. The electrochemical performance measurements of the cell revealed that elevated cell voltages enhance the charge acquisition of Mn 2+ ions more than protons, thereby improving manganese recovery efficiency. However, this also introduces higher non-Faradaic losses, resulting in an increase in the specific energy consumption and a decrease in the overall energy conversion efficiency. The application of a superimposed pulse—featuring a peak voltage of 5.6 V and a base voltage of 3.5 V—proved beneficial in maintaining cathodic protection, supporting ion replenishment, reducing current oscillations, and sustaining the hydrogen evolution reaction. Moreover, pulse frequency was found to significantly influence productivity, while the duty cycle had a marked impact on improving current efficiency (99.43 %), overall energy conversion efficiency (37.11 %), manganese content (28.50 %), and other performance metrics. A duty cycle of 50 % at 50 Hz was identified as optimal, reducing specific energy consumption by 4.33 % compared to the conventional direct current operation. • A novel hybrid manganese redox cycle integrated with PEM electrolysis was developed for efficient hydrogen production. • Superimposed pulse electrolysis was systematically analysed to study catholyte properties. • A peak voltage of 5.6 V and base voltage of 3.5 V ensured stable hydrogen production. • Optimal conditions (50 % duty cycle at 50 Hz) resulted in a 4.33 % reduction in specific energy consumption. • Pulse parameters (frequency and duty cycle) significantly influenced current efficiency, and Mn recovery.