Towards the implementation of a more economical catalyst for hydrogen production in microbial electrolysis cells

<ns3:p> Background Microbial electrolysis cells (MECs) enable hydrogen production while simultaneously oxidizing the organic matter present in wastewater. However, the efficiency of this process is limited by the slow kinetics of the cathodic reaction, which require the use of a catalyst. Platinum (Pt) is frequently employed because of its high catalytic performance; however, its cost precludes large-scale applications. This study investigates alternative cost-effective catalysts (Cu <ns3:sub>100</ns3:sub> , Ni <ns3:sub>100</ns3:sub> , Ni <ns3:sub>85</ns3:sub> Mo <ns3:sub>15</ns3:sub> , Ni <ns3:sub>64</ns3:sub> Fe <ns3:sub>18</ns3:sub> Mo <ns3:sub>18,</ns3:sub> and Ni <ns3:sub>76</ns3:sub> Fe <ns3:sub>16</ns3:sub> Mo <ns3:sub>8</ns3:sub> ) composed of non-noble metals. Methods The catalysts were electrodeposited on a carbon cloth and felt electrodes, and Cu <ns3:sub>100</ns3:sub> and Ni <ns3:sub>100</ns3:sub> were manually deposited to compare the electrochemical and physical deposition methods. Techniques such as Scanning Electron Microscopy, Linear Sweep Voltammetry, and Electrochemical Impedance Spectroscopy were used for the characterization. Results The results demonstrated that electrochemical deposition was a more efficient and cost-effective method than manual deposition, and was therefore excluded. Among the catalysts, Ni <ns3:sub>64</ns3:sub> Fe <ns3:sub>18</ns3:sub> Mo <ns3:sub>18</ns3:sub> demonstrated comparable performance to Pt in terms of the current density (1.2 mA·cm <ns3:sup>−2</ns3:sup> ) and uniform deposition. The carbon felt electrodes demonstrated superior performance compared to carbon cloth, which can be attributed to their larger electroactive areas. Carbon felt electrodes outperformed carbon cloth, attributed to their larger electroactive area, achieving up to 9% higher current density with Ni <ns3:sub>64</ns3:sub> Fe <ns3:sub>18</ns3:sub> Mo <ns3:sub>18</ns3:sub> . Conclusions This study suggests that a more economical alloy, such as Ni <ns3:sub>64</ns3:sub> Fe <ns3:sub>18</ns3:sub> Mo <ns3:sub>18</ns3:sub> on carbon felt electrodes is a promising alternative to Pt for enhancing H₂ production in MECs. </ns3:p>