Multifunctional MXene/FeNi₃ heterointerfaces enable remarkable microwave absorption and integrated energy conversion

To fulfill the electromagnetic wave absorption (EMA) demands for radar stealth and oxygen evolution reaction (OER) for seawater electrolysis on marine floating wind-power hydrogen production platforms, this study reports the rational design and construction of multifunctional Ti₃C₂T_x MXene/FeNi₃ heterostructures via electrostatic adsorption and subsequent solvothermal reduction. The resulting heterostructures simultaneously achieve high-efficiency tunable EMA, photothermal conversion and greatly enhanced OER performance. Specifically, FeNi₃ particles strengthen the synergistic interactions between heterointerface resonance and magnetic coupling, and the tailored heterostructures facilitate multiple scattering, both of them result in matched impedance and optimized electromagnetic attenuation. As expected, the heterointerfaces of MXene/FeNi₃-2 display a broad effective absorption bandwidth of 7.47 GHz at 2.04 mm, a remarkable reflection loss of −65.92 dB, and a radar cross-section as low as −45.98 dB·m². Meanwhile, benefiting from the enhanced localized surface plasmon resonance, the heterointerfaces demonstrate rapid and reversible photothermal response, reaching equilibrium temperatures of 56.7–105.2 °C under optical power densities of 100–200 mW·cm⁻² with excellent sustained performance over 6 h. Additionally, outstanding OER activity is achieved with a low overpotential 424 mV and robust long-duration stability over 300 h. This work offers a feasible strategy for high-performance EMA and a new reference for advanced multifunctional materials for marine hydrogen platforms.