Hydrogen Production Performance of Industrial NiCrMo276 Electrodes in Alkaline Sulfide Electrolysis

Hydrogen sulfide (H2S) is a toxic sulfur-containing by-product generated in refining, gas processing, and decomposition processes. Its electrochemical treatment under alkaline conditions offers a potential route for simultaneous hydrogen production and sulfide conversion. Although alkaline sulfide electrolysis has been investigated for several decades, quantitative information on the performance of industrial corrosion-resistant electrodes remains limited. In this work, industrial NiCrMo276 alloy electrodes were evaluated for hydrogen production in a batch alkaline sulfide electrolysis system. Graphite was used as a reference material in an initial electrode screening, in which NiCrMo276 exhibited a substantially higher current response under identical electrolysis conditions. Based on this screening, NiCrMo276 was selected for subsequent evaluation of the effects of applied cell voltage and NaHS concentration on the electrochemical response. At an applied cell voltage of 1.8 V and a NaHS:NaOH molar ratio of 1.25:1, hydrogen was produced at 200 mL h−1, corresponding to a current density of 33 mA cm−2 and a Faradaic efficiency of 92%. The specific electricity consumption was 52.4 kWh kg−1 H2. Complementary sulfur analyses indicated incomplete sulfide conversion and a marked evolution of the dissolved sulfur composition, particularly toward thiosulfate, although the measured sulfur distribution could not be attributed exclusively to electrochemical reactions. Post-electrolysis SEM–EDX observations showed that NiCrMo276 retained a relatively well-defined surface morphology, particularly at the cathode, while the graphite surface exhibited substantial intrinsic heterogeneity. Overall, the combination of high Faradaic efficiency, hydrogen productivity, and substantially higher current response than graphite highlights NiCrMo276 as a promising electrode material for alkaline sulfide electrolysis.