Synthesis of Er3+/Zn2+ co-doped Bi2WO6 with highly efficient photocatalytic performance under natural indoor weak light illumination

A novel Zn2+ and Er3+ co-doped Bi2WO6 (Zn-Er-Bi2WO6) photocatalysts have been successfully synthesized for the first time. The photodegradation activity of the obtained samples was investigated under natural indoor weak light illumination using the Rhodamine dye in aqueous solution. While the light intensity of degradation process is measured to be about 2000 Lux (merely 1% of 300 W Xe lamp), it is amazing that RhB dye can be completely degraded within 150 min, but only 36% of dye was degraded by pure Bi2WO6 at the same condition. In all photocatalysts including pure Bi2WO6, Zn-Bi2WO6, Er-Bi2WO6, Zn-Er-Bi2WO6 series, 9%Zn-7%ErBi2WO6 presents the best degradation efficiency and corresponding kinetic constant is 0.022 min(-1), approximately 8 times higher than that (0.0029 min(-1)) of pure Bi2WO6. This natural indoor weak sunlight-driven degradation reaction does not need an extra optical system that inevitably consumes fossil resources, therefore it is a green, energy-saving environmental cleaning strategy. In addition, Zn-Er-Bi2WO6 is only weakly sensitive to pH changes, indicating its potential application in the aqueous systems with different pH values. Also, a possible mechanism is proposed to explain the procedure of photodegradation.