Non‐noble metal based broadband photothermal absorbers for cost effective interfacial solar thermal conversion

In recent years, noble metal‐based solar absorbers have been extensively studied as their pronounced plasmonic resonances and high solar‐to‐thermal conversion efficiency. However, the high cost of noble metals is the unavoidable roadblock restricting the way towards scalability. In this work, we report a nickel‐based photothermal absorbers, which is capable of realizing an average solar absorption of ∼97% in the range of 400–2500 nm originating from relatively weaker collective plasmonic resonances but more pronounced single electron excitation. Importantly, it is easily fabricated via the straightforward physical deposition and cost‐effective with a raw material price of ∼0.3% gold and ∼20% of silver. We used it for interfacial solar vapor generation and realized an evaporation rate of ∼0.9 kg m −2 h −1 under one sun, almost comparable to the counterparts made from noble metals. The excellent performance combined with the cost effective and scalable fabrication process makes it be a promising candidate for mass off‐grid solar desalination.