Unlocking the potential of NiV-LDH@Mn2O3 heterostructure via band gap modulation for enhanced water splitting

Abstract

Overall water-splitting reactions provide significant challenges for the rational design and manufacture of electrocatalysts with exceptional capabilities and long-term durability. NiV-LDH is a promising electrocatalyst for OER; however, its low conductivity limits its performance towards total water splitting. This study describes the development of a novel composite material, NiV-LDH@Mn₂O_3. Mn₂O₃ indirectly enhances the conductivity of the composite by pulling electrons from NiV-LDH via formed heterojunction. The band gap (1.35 eV) from the Tauc plot analysis further shows the increased electrical conductivity after the heterostructure. Furthermore, the number of active sites increased by 5.34 and 18 times compared with the bare NiV-LDH and Mn₂O₃, respectively. This increased active sites facilitate a simultaneous enhancement in TOF values of 6.945 × 10⁻⁴ and 0.001 s⁻¹ for OER and HER, respectively. In 1 M KOH solution, NiV-LDH@Mn₂O₃ requires overpotentials of 298 and 185 mV for OER and HER to achieve a 50 mA cm⁻² current density with 54 and 48 h of long-term stability, respectively. Moreover, it shows a low cell voltage of 1.604 V to reach a 10 mA cm⁻² current density with 70 h stability. Besides, the specific activity after the formation of the heterostructure is increased by 1.8 times compared with the bare materials. This heterostructure strategy paves a unique way for the sustainable production of hydrogen from the electrocatalytic water splitting technique.