Desenvolvimento e aplicação de fonte de corrente Howland para avaliação da eletrólise pulsada da água

Abstract

Pulsed water electrolysis has emerged as a promising strategy to mitigate limitations inherent to conventional electrolysis, particularly those associated with activation and ohmic overpotentials, mass transport phenomena, and the dynamic behavior of the electrical double layer. However, experimental investigation of pulsed regimes requires current sources capable of delivering precise, stable, and reproducible waveforms under dynamic variations of the electrolytic cell impedance. In this context, this dissertation presents the development, implementation, and application of a Howland Current Source (HCS) specifically designed for pulsed electrolysis studies. The Howland topology was selected due to its high output impedance, linearity, and ability to supply modulated currents with minimal load dependence, which are essential features for accurate pulse control. The developed system was employed both for electrical characterization of the electrolytic cell, through transient analysis of the electrical double layer, and for comparative evaluation between continuous and pulsed electrolysis. Experimentally, pulsed electrolysis achieved a maximum relative energy efficiency gain of 9.72%, reaching efficiencies up to 31.1% when operated at frequencies between 40 and 50 kHz and duty cycles ranging from 20% to 50%, under a current density of approximately 0.5 A/cm². Under these conditions, a reduction of up to 700 mV in the average cell voltage was observed, indicating partial mitigation of electrochemical overpotentials. The Howland current source exhibited a maximum mean squared error of 0.053 relative to an ideal waveform, demonstrating stable and reproducible dynamic performance even at high frequencies. These results highlight the HCS as a low-cost, high-fidelity experimental tool for advanced investigations of pulsed water electrolysis and green hydrogen production.