Sulfur/Gadolinium-Codoped TiO₂ Nanoparticles for Enhanced Visible-Light Photocatalytic Performance

Table 1

Indirect band gap and percentage degradation after exposure to visible-light radiation.

Sample	Indirect band gap (eV)	Degradation (%)^a	k (min^−1)^b
Commerrcial TiO2	3.08	34.8	6.5×10^−3±0.0004
TiO2-S/Gd^3+ (0.0% Gd^3+)	3.04	56.6	1.7×10^−2±0.0019
TiO2-S/Gd^3+ (0.2% Gd^3+)	2.90	88.1	4.8×10^−2±0.0031
TiO2-S/Gd^3+ (0.4% Gd^3+)	2.86	92.6	4.1×10^−2±0.0105
TiO2-S/Gd^3+ (0.6% Gd^3+)	2.63	100.0	5.6×10^−2±0.0092
TiO2-S/Gd^3+ (0.8% Gd^3+)	2.75	67.7	6.4×10^−2±0.0131
TiO2-S/Gd^3+ (1.0% Gd^3+)	2.95	70.1	1.9×10^−2±0.0017

aMeasured after reaction for 50 min. ^bApparent rate constant calculated from the linear fitting of ln(𝐶₀/𝐶) versus reaction time after 40 min.