Figure 5From: Self-organized vanadium and nitrogen co-doped titania nanotube arrays with enhanced photocatalytic reduction of CO2 into CH4Photocurrent responses in light on-off process at applied voltage. Of 0.4 V (vs. SCE) under UV irradiation for (curve a) N-TiO2, (curve b) VN0, (curve c) VN0.5, (curve d) VN1, (curve e) VN3, and (curve f) VN5.Back to article page