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.- Ministry of Trade, Industry & Energy. - Qatar National Research Fund (QNRF) grant #NPRP 10-1210-160019. - Ministry of Trade, Industry and Energy (MOTIE) grant #20011360. - National Research Foundation of Korea (NRF) grant #2018R1A6A1A03024962, 2019M1A2A2065616, 2019R1A2C2002602