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

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.