Solar hydrogen production via pulse electrolysis of aqueous ammonium sulfite solution

A long-standing challenge for hydrogen production via solar water splitting is the efficiency of converting solar energy to hydrogen chemical energy. Thermolysis, photocatalysis and electrolysis are three basic solar water splitting processes that utilize solar thermal, photonic and electrical energies. A technology using a combination of these processes can utilize a wider spectrum of solar radiation, thereby enhancing the efficiency of solar energy conversion. Due to the simplicity and maturity of photovoltaic (PV) cells and electrolyzer cells, solar hydrogen production via PV cells plus water electrolysis has been implemented and widely used as a bench mark process. The present study focuses on solar hydrogen production via direct current pulse electrochemical oxidation of aqueous ammonium sulfite solutions, one important step in solar sulfur–ammonia (S-NH3) thermochemical water splitting cycles. The results show that pulsating electrolysis enhances the efficiency of hydrogen production. The effects of pulsating parameters (such as pulsating on time and off time, frequency and duty cycle) on hydrogen evolution rates are discussed in detail.

► H2 production via electrolysis of aqueous (NH4)2SO3 solution is investigated.
► DC pulse electrolysis of (NH4)2SO3 solution shows potentials for energy saving.
► Effects of DC pulse electrolysis parameters for H2 production are discussed.