This study investigates the improvement of spinel OER electrochemical properties through doping strategy for water splitting. The performance of spinel SnMn₂O₄ was significantly improved by incorporating Sm doping during the synthesis process using a cost-effective and efficient hydrothermal method. The nano-flakes morphology exhibited a higher surface area, providing more active sites. Sm-doped SnMn₂O₄ catalyst showed a remarkable overpotential of 212 mV at 10 mA cm⁻² and a Tafel slope of 37 mV dec⁻¹. The catalyst exhibited exceptional stability after 5000 cycles and less impedance characteristics. The addition of Sm dopant increased surface area and conductivity, significantly enhancing OER activity. This study offers enhanced OER catalysts with a broader perspective on the relation between the structure and activity of spinel for more effective energy generation devices. Water electrolysis is considered an appealing technology for generating H₂ as a clean fuel through the electrochemical dissociation of water. The effectiveness and productivity of these technologies are greatly impacted by two electrochemical processes: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the OER is extremely slow due to the existence of four proton-coupled electron channels. The widespread adoption of ruthenium and iridium-based oxides is limited by their high price and restricted availability. Therefore, the purpose was to create affordable transition metal compounds for OER that demonstrate distinctive redox behavior, ionic conductivity and electronic properties. Recent research has centered around creating new transition metal-based compounds that exhibit exceptional electrochemical OER properties. Spinel-structured transition metals have gained significant interest as catalysts for OER activity due to their many benefits. These features include their highly adaptable electronic band structures, affordable price, sufficient availability in Earth's reserves, rapid electrochemical kinetics and improved long-term electrocatalyst stability. Recent studies have shown that transition metals with high valence states and a spinel structure have excellent performance in OER. The d-band of the transition metal, which is highly oxidized, usually moves downward to align with the oxygen p-band, leading to formation of vacancies in oxygen p-band. Thus, lattice oxygen species exhibit chemical reactivity and electrophilicity, making them highly oxidizing and capable of directly participating in OER as active sites. Most bimetallic transition materials face limitations in their conductivity and active site concentrations, which greatly restrict their potential applications. These limitations arise from the volume changes that occur during electrochemical reactions. Refinements made at the molecular level, including the incorporation of transition-metal atoms and meticulous structural design, have the potential to significantly enhance the electrocatalytic performance, reaction kinetics and activity of electrocatalysts. Structures that possess vacancies, nanosheets, nanoflakes and needle-like shapes exhibit a greater number of exposed surfaces and a lower concentration of atoms in close proximity compared to large,This study investigates the improvement of spinel OER electrochemical properties through doping strategy for water splitting. The performance of spinel SnMn₂O₄ was significantly improved by incorporating Sm doping during the synthesis process using a cost-effective and efficient hydrothermal method. The nano-flakes morphology exhibited a higher surface area, providing more active sites. Sm-doped SnMn₂O₄ catalyst showed a remarkable overpotential of 212 mV at 10 mA cm⁻² and a Tafel slope of 37 mV dec⁻¹. The catalyst exhibited exceptional stability after 5000 cycles and less impedance characteristics. The addition of Sm dopant increased surface area and conductivity, significantly enhancing OER activity. This study offers enhanced OER catalysts with a broader perspective on the relation between the structure and activity of spinel for more effective energy generation devices. Water electrolysis is considered an appealing technology for generating H₂ as a clean fuel through the electrochemical dissociation of water. The effectiveness and productivity of these technologies are greatly impacted by two electrochemical processes: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the OER is extremely slow due to the existence of four proton-coupled electron channels. The widespread adoption of ruthenium and iridium-based oxides is limited by their high price and restricted availability. Therefore, the purpose was to create affordable transition metal compounds for OER that demonstrate distinctive redox behavior, ionic conductivity and electronic properties. Recent research has centered around creating new transition metal-based compounds that exhibit exceptional electrochemical OER properties. Spinel-structured transition metals have gained significant interest as catalysts for OER activity due to their many benefits. These features include their highly adaptable electronic band structures, affordable price, sufficient availability in Earth's reserves, rapid electrochemical kinetics and improved long-term electrocatalyst stability. Recent studies have shown that transition metals with high valence states and a spinel structure have excellent performance in OER. The d-band of the transition metal, which is highly oxidized, usually moves downward to align with the oxygen p-band, leading to formation of vacancies in oxygen p-band. Thus, lattice oxygen species exhibit chemical reactivity and electrophilicity, making them highly oxidizing and capable of directly participating in OER as active sites. Most bimetallic transition materials face limitations in their conductivity and active site concentrations, which greatly restrict their potential applications. These limitations arise from the volume changes that occur during electrochemical reactions. Refinements made at the molecular level, including the incorporation of transition-metal atoms and meticulous structural design, have the potential to significantly enhance the electrocatalytic performance, reaction kinetics and activity of electrocatalysts. Structures that possess vacancies, nanosheets, nanoflakes and needle-like shapes exhibit a greater number of exposed surfaces and a lower concentration of atoms in close proximity compared to large,