Photothermal enhancement of water electrolysis using carbon black nanofluids

This study investigates polyvinylpyrrolidone (PVP)-stabilized carbon black (CB) nanofluids for photothermally assisted alkaline water electrolysis using a 0.5 M potassium hydroxide (KOH) electrolyte. The effects of CB concentration and external irradiation, controlled by varying the distance between a halogen lamp and the electrolysis apparatus, were evaluated in terms of hydrogen production, energy consumption, and efficiency. Irradiation increased electrolyte temperature, current, and hydrogen production, with the strongest enhancement at a lamp distance of 10 cm. At the optimum CB concentration of 0.005 wt%, the time required to produce 60 mL of hydrogen decreased by approximately 15%, while specific electrical energy consumption decreased by 7%–8%. Faradaic efficiency remained close to 100%, and photothermal performance was stable during repeated irradiation and storage. These findings demonstrate the potential of CB nanofluids for photothermal enhancement of alkaline electrolysis while highlighting the importance of thermal management and energy utilization.