A green and efficient strategy to utilize spent SCR catalyst carriers: in situ remediation of Cu@TiO2 for photocatalytic hydrogen evolution

Abstract

The selective utilization of titanium dioxide (TiO₂) carriers in spent selective catalytic reduction (SCR) catalysts offers a promising strategy to alleviate environmental pollution and recover high-value resources. Herein, we report a green and sustainable method for the in situ remediation of TiO₂ carriers from spent SCR catalysts with a short process using a simple impregnation method to prepare recovered CR-TiO₂ with the deposition of Cu. When employed in photocatalytic hydrogen production, CR-TiO₂ achieved a hydrogen production rate of 388 μmol g⁻¹ h⁻¹, which was 1.75 times higher than that of C-TiO₂ (commercial TiO₂). Experimental results and DFT calculations demonstrated that the doping of Cu species broadened the light absorption range of TiO₂ and promoted water dissociation, thus enhancing its photocatalytic performance. Finally, the process was evaluated by life cycle assessment (LCA), which showed a nearly 67.8%, 71.8%, 66.5%, and 83.2% reduction in fossil fuel depletion, ozone depletion, carbon dioxide and sulfur dioxide emissions, respectively, compared to the conventional electronic-grade TiO₂ synthesis method. This work provides a sustainable way to produce clean, green energy by utilizing titanium resources recovered from spent SCR catalysts. Furthermore, it provides new insights into turning waste into treasure and opens up a new way to alleviate environmental problems.