Multifunctional porous Ho–Ce MOF coupled with Ti3C2Tx/PVP nanosheets for advanced battery–supercapacitors and sustainable water electrolysis

The development of advanced nanostructured electrode materials for supercapacitors and sustainable energy applications remains a significant challenge, particularly in achieving a high accessible surface area that promotes efficient electrode–electrolyte interactions and facilitates rapid charge-transfer kinetics. This study involves the synthesis of interconnected nanostructured holmium-doped cerium metal-organic frameworks (Ho@Ce-MOF) and titanium carbide (Ti 3 C 2 T x ) MXene by a cost-efficient hydrothermal technique. The Ho@Ce-MOF/Ti 3 C 2 T x , additionally doped with polyvinylpyrrolidone (PVP), is subjected to extensive characterization to evaluate its structural, morphological, and electrochemical properties by various methodologies. Electrodes fabricated from the Ho@Ce-MOF/Ti 3 C 2 T x /PVP composite have a substantial specific capacity (Qs) of 562 C/g. The fabricated asymmetric supercapacitor (ASC) delivers an impressive energy density (E n ) of 69.5 Wh kg −1 and power density (P n ) of 1121 W kg −1 at 1 A g −1 , while exhibiting excellent long-term cycling stability with 85.1% capacity retention after 10,000 charge–discharge cycles.Additionally, the electrocatalytic performance of the modified Ho@Ce-MOF/Ti 3 C 2 T x /PVP electrode was systematically evaluated toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The electrode exhibited efficient OER activity, requiring an overpotential (η) of 216 mV to achieve 10 mA cm −2 , with a Tafel slope of 102.7 mV dec −1 . Notably, superior HER kinetics were demonstrated by a low overpotential of 69.5 mV at −10 mA cm −2 and a Tafel slope of 41.8 mV dec −1 , together with excellent electrochemical stability. These results highlight the favorable interfacial charge-transfer characteristics and bifunctional electrocatalytic activity of Ho@Ce-MOF/Ti 3 C 2 T x /PVP, establishing it as a promising multifunctional electrode material for high-performance supercapacitors and sustainable hydrogen-energy technologi es .