Utilizing E-Waste for Construction of Magnetic and Core-Shell Z-Scheme Photocatalysts: An Effective Approach to E-Waste Recycling

The increasingly large stream of e-waste is seriously threatening the environment; meanwhile, global energy shortage is on the rise. Based on the principles of energy regeneration and waste utilization, we introduced a win-win approach to utilize waste capacitors for construction of magnetic and core-shell Z-scheme Nb-Pb-codoped BaTiO/Ni-Pd@graphite-like carbon nitride (g-CN) photocatalysts for H evolution. Using simple ball-milling, waste capacitors were transformed to Nb-Pb-codoped BaTiO/Ni-Pd-Ag-Sn nanoparticles and g-CN was coated on the nanoparticles, forming a core-shell structure. The Ni-Pd acted as the electron mediator in the Z-scheme, and Ag-Sn also facilitated the electron transfer. Moreover, Ni made the Z-scheme magnetically separable. The Z-scheme showed a remarkably enhanced photocatalytic H evolution rate, which was 22.2 times higher than that of g-CN. Such an enhanced photocatalytic performance was attributed to the special Z-scheme and core-shell structure, improving the light adsorption, increasing the Brunauer-Emmett-Teller (BET) surface area, facilitating the efficient separation of electron-hole pairs, and maintaining the strong redox ability of charge carriers. Furthermore, the photoluminescence analysis combined with density functional theory (DFT) calculations provided the basis for the Z-scheme mechanism. This study adequately utilized the composition of e-waste to construct a highly efficient and magnetically separable Z-scheme for H generation, which realizes energy regeneration, waste recycling, and environmental protection.