Light-to-heat conversion and photothermal hydrogen evolution over magnetic nitinol photocatalyst

Development of efficient photothermal catalysts made of earth-abundant elements is of prime importance for heterogeneous photocatalysis driven by solar light. Herein, we report for the first time the synthesis of NiTi@TiO2/Ni core-shell-satellite nanoparticles from pristine nitinol nanopowder (NiTi) by simple and easily scalable ultrasonically assisted hydrothermal treatment in pure water (T = 200 C-degrees, P = 14 bar, f = 20 kHz, P-ac = 17 W, tau = 3 h). Prepared material exhibits unique set of properties, such as strong capability of light-to-heat conversion, good magnetization, high stability, and remarkable thermally assisted photocatalytic hydrogen production (5.5 mmol h(-1) g(-1) at T = 90 C-degrees). The core-shell-satellite morphology of NiTi@TiO2/Ni particles maximizes the contact area between the heat generating metallic core and photocatalytically active TiO2/Ni nanocrystalline shell providing the most efficient photothermal effect in the processes of H-2 production and CO2 methanation without CO emission. In addition, significant magnetic susceptibility of the NiTi@TiO2/Ni nanoparticles allows their easy recovery from solution with an external magnetic field. Noncongruent surface oxidation of nanoalloys reported in this work paves the way to the preparation of new generation of catalysts with advanced photothermal properties.