Light-free degradation of hydrogen sulfide via a Cu+ /Cu2+ redox cycle on a titanium dioxide supported copper hydroxide nitrate catalytic adsorbent.

The performance of titanium dioxide-supported copper hydroxide nitrate (TiO2-Cu2(OH)3NO3) as a light-free catalytic adsorbent is studied for the degradation of hydrogen sulfide (H2S). These composites are coded as TC-x, where T and C denote the TiO2 support and Cu2(OH)3NO3 active phase, respectively with x as the nominal copper weight percentage (1-10 %). The H2S removal efficiency (XH₂S) of the prototype air purifier, when evaluated using TC-1, -2, -5, and -10 systems (0 % relative humidity over 240 s) reaches 66 %, 96.5 %, 100 %, and 100 %, respectively, while that of the pure TiO₂ attains 3 %. Their performance generally hinges on both H2S concentration and RH levels to record a maximum kinetic removal rate of 14.1 mmol g-1 h-1 (at XH₂S = 10 %) and a maximum capacity of 10.3 mg g-1, when tested against 20 H2S (80 % RH). A maximum clean air delivery rate of 46.4 L min-1 is also achieved at 5 ppm H2S (50 % RH). The remarkable performance of TC-5 is primarily attributed to a highly efficient Cu+/Cu2+ redox cycle through the well-dispersed copper hydroxide nitrate on the high-surface-area TiO2 scaffold which stabilizes reactive intermediates. Furthermore, in situ DRIFTS analysis reveals that water vapor and oxygen work synergistically to enhance H2S removal.