A generic method is presented for fabricating ultrathin nanosheet arrays of two-dimensional metal-organic frameworks (MOFs) on various substrates via a dissolution-crystallization mechanism. The resulting NiFe-based MOF arrays exhibit superior electrocatalytic performance for oxygen evolution reaction (OER) with a low overpotential of 240 mV at 10 mA cm⁻² and high turnover frequency of 3.8 s⁻¹ at 400 mV overpotential. The material also shows excellent stability, maintaining activity for 20,000 seconds. The MOF arrays demonstrate high catalytic activity for both OER and hydrogen evolution reaction (HER), as well as overall water splitting. The material's performance is attributed to its ultrathin structure, which exposes active metal sites, combined with hierarchical porosity and enhanced electrical conductivity. The MOF arrays are synthesized via a one-step chemical bath deposition method, and their structure is characterized by various techniques including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The MOF arrays show high catalytic activity and stability, outperforming other MOF-based catalysts and commercial benchmarks. The study highlights the potential of 2D MOF nanosheets as efficient electrocatalysts for water splitting and other catalytic reactions. The method is generic and can be adapted for various MOF materials and substrates. The results demonstrate that MOFs can be effective electrocatalysts when designed with appropriate structural features.A generic method is presented for fabricating ultrathin nanosheet arrays of two-dimensional metal-organic frameworks (MOFs) on various substrates via a dissolution-crystallization mechanism. The resulting NiFe-based MOF arrays exhibit superior electrocatalytic performance for oxygen evolution reaction (OER) with a low overpotential of 240 mV at 10 mA cm⁻² and high turnover frequency of 3.8 s⁻¹ at 400 mV overpotential. The material also shows excellent stability, maintaining activity for 20,000 seconds. The MOF arrays demonstrate high catalytic activity for both OER and hydrogen evolution reaction (HER), as well as overall water splitting. The material's performance is attributed to its ultrathin structure, which exposes active metal sites, combined with hierarchical porosity and enhanced electrical conductivity. The MOF arrays are synthesized via a one-step chemical bath deposition method, and their structure is characterized by various techniques including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The MOF arrays show high catalytic activity and stability, outperforming other MOF-based catalysts and commercial benchmarks. The study highlights the potential of 2D MOF nanosheets as efficient electrocatalysts for water splitting and other catalytic reactions. The method is generic and can be adapted for various MOF materials and substrates. The results demonstrate that MOFs can be effective electrocatalysts when designed with appropriate structural features.