Engineering a Versatile Spectrally Selective Absorber for Moderate‐ and Low‐Temperature Application with Gradient High‐Entropy Nitride Nanofilms

Spectrally selective absorber with superior thermal stability and optical properties is crucial for photothermal conversion applications, including evaporation, anti‐icing, medical sterilization, photothermal catalysis, and solar‐thermal power. Efforts are being made to develop entropy‐stabilized high‐entropy ceramics as high‐performance functional materials, which promise a wide range of potential applications in the fields of energy storage and conversion owing to their diverse compositions and outstanding physical and chemical properties. Herein, an entropy‐stabilized strategy is used to boost the performance of spectrally selective absorbers by carefully choosing a high‐entropy alloy (TiVCrAlZr) target with a reasonable element design, which exhibits a good solar absorptance (α = 96.1%) and low thermal emittance (ϵ = 7.8%). Long‐term thermal stability investigation demonstrates that the entropy‐stabilized absorber could endure at 400 °C for 168 h. Under the irradiation of simulated sunlight, the surface temperature of the absorber can reach up to 105 °C, which is essential for middle‐ and low‐temperature applications. Overall, this work provides significant insights into the spectral selectivity of high‐entropy alloy nitrides and offers a new strategy for designing and developing moderate and low solar selective absorbing coatings via a high‐entropy strategy.