American Chemical Society
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TiN, ZrN, and HfN Nanoparticles on Nanoporous Aluminum Oxide Membranes for Solar-Driven Water Evaporation and Desalination

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journal contribution
posted on 2020-03-06, 17:35 authored by Emily Traver, Reem A. Karaballi, Yashar E. Monfared, Heather Daurie, Graham A. Gagnon, Mita Dasog
Water desalination via thermal evaporation using plasmonic nanostructures which harness and convert solar irradiation to provide the requisite heat input is gaining interest as a scalable and sustainable method to address global freshwater scarcity. To meet growing freshwater demand in such a manner, new, inexpensive plasmonic nanomaterials that exhibit high solar-to-vapor-conversion efficiencies are being sought. Here, plasmonic metal nitride interfaces consisting of TiN, ZrN, and HfN nanoparticles (NPs) with sizes ranging between 10 and 20 nm drop-cast onto nanoporous anodic aluminum oxide (AAO) membranes were analyzed for water evaporation and desalination. Evaporation rates of 1.10 ± 0.05, 1.27 ± 0.04, and 1.36 ± 0.03 kg m–2 h–1 and solar-to-vapor efficiencies of 78, 88, and 95% were observed for TiN, ZrN, and HfN, respectively, under 1 sun illumination. Computational analysis of the solar absorption cross-section of the nitride NPs was consistent with this trend. The HfN–AAO interface was further explored for desalination purposes using Atlantic Ocean saltwater as a source and showed evaporation rates of 1.2 ± 0.2 and 6.1 ± 0.4 kg m–2 h–1 and solar-to-vapor efficiencies of 87 and 99% under 1 and 4 suns, respectively. Inductively coupled plasma mass spectrometry (ICP-MS) measurements showed effective removal of the major metal ions (Na+, K+, Mg2+, and Ca2+) following the desalination process using the HfN–AAO interface.