Single-Pot Solvothermal Synthesis of Single-Crystalline Nickel-Metal Organic Framework Nanosheets for Direct Iron Fuel Cell Applications

The usage of iron leads to the generation of large quantitiesofscrap iron, which is hazardous to health and causes environmentalpollution. Recycling techniques are expensive and involve high energyconsumption. Instead of recycling, scrap iron can be used as an alternativepotential source for fuel cell applications. Here, we report the synthesisof a single-crystalline nickel-based MOF (Ni-MOF), via a single-potsolvothermal technique, as an electrocatalyst to produce hydrogenfrom scrap iron. Detailed characterization reveals the nanosheet morphologyof the Ni-MOF obtained by FESEM; at the same time Ni-MOF formationis confirmed through the XRD spectrum. The as-synthesized Ni-MOF isdeposited on nickel foam (NF) and used as an electrocatalyst (Ni-MOF/NF)which exhibits a peak current density of 8.8 A/g (scrap) and responsetoward hydrogen production at an onset potential of 0.5 V (vs Hg/HgO).The improved performance of the Ni-MOF/NF electrode is ascribed tothe high catalytic activity of Ni-MOF owing to the multiple oxidationstates of Ni (i.e., Ni2+/3+); the reversible transformationbetween +2 and +3 oxidation states results in the redox peaks of thecatalytic reaction; and the organic ligands in the MOF structure helpin improving the conductivity and pore size of the material. The Ni-MOF/NFelectrode exhibits outstanding stability with & SIM;88.1 and & SIM;72.9%capacity retention after 100,000 and 50,000 s for scrap and iron metalpowder, respectively. This proves that the theickel metal-organicframework coated on nickel foam (Ni-MOF/NF) electrocatalyst is anoutstanding material for iron source-based fuel cell applications.

Automated summary

The usage of iron leads to the generation of hazardous scrap iron, but it can be used as an alternative source for fuel cell applications. Here, a single-crystalline nickel-based MOF (Ni-MOF) was synthesized as an electrocatalyst to produce hydrogen from scrap iron. The Ni-MOF/NF electrode shows improved performance due to the high catalytic activity of Ni-MOF and the organic ligands in the MOF structure. This Ni-MOF/NF electrode exhibits outstanding stability and is suitable for iron source-based fuel cell applications.