Reduced titania nanorods and Ni–Mo–S catalysts for photoelectrocatalytic water treatment and hydrogen production coupled with desalination

This study presents a ternary hybrid solar desalination process coupled with photoelectrocatalytic water treatment and H₂ production in a single device. The desalination of brackish water in the desalination cell is initiated via photoinduced charge generation with a thermochemically reduced TiO₂ nanorod array photoanode. The chlorides transferred to the neighboring anolyte at ion-transport efficiency of ∼100% are photoelectrochemically transformed into reactive chlorine species responsible for the decomposition of urea into nitrate in the anolyte. Simultaneously, the H₂ production with a Ni–Mo–S (Ni₂S₃/MoS₂) composite catalyst grown onto porous Ni substrate is achieved at Faradaic efficiency of ∼90% in the catholyte concentrated with desalted Na⁺. Regardless of the operation condition, the H₂ energy contributes to the reduction in the energy consumption for desalination by 25%–30%. The overall ternary hybrid process is understood systematically, and the physiochemical properties and electrochemical behavior of the Ni–Mo–S catalysts are examined.