Table 2 Quantification results with corresponding operational conditions for PEC-COD sensors

WE: TiO₂/ITO, SE: NaNO₃, CE: Pt.

RE: Ag/AgCl, and Xe lamp

TiO₂ monolayer: Th = 0.18 mm, A = 0.75 cm², anodic compartment: V = 13.5 µL at 23 °C, E_bias = +0.3 V (vs. Ag/AgCl), I_light = 6.6 mW cm⁻² (P = 150 W), and t_assay = 1–5 min

0.2 (1.2% RSD)

≤200

PEC-COD = 0.9957 ThCOD – 0.2333 (R² = 0.990, calibration).

PEC-COD = 1.0040 COD—0.0384 (R² = 0.987, n = 15) (std)

^44,90

TiO₂ monolayer: Th = 0.10 mm, A = 0.785 cm², anodic compartment: V = 7.85 µL at 23 °C, E_bias = +0.2 V (vs. Ag/AgCl)

0.2–360

PEC-COD = 1.024 COD (std, R² = 0.992, n = 28)

WE: TiO₂/ITO, CE: Pt, SE = NaClO₄ flux

E_Bias = +0.3 V (vs. Ag/AgCl), J_rate = 0.3 mL min⁻¹, V = 13 µL at 23 °C.

1 (0.8% RSD)

≤100

PEC-COD = 1.0145 ThCOD + 0.3192 (R² = 0.9895)

⁴⁵

WE = TiO₂/ITO, SE = NaNO₃

TiO₂ monolayer: A = 0.2 cm², anodic compartment: V = 2.0 µL at 23 °C, d_(RE-WE) = 3 mm, d_(RE-WE) = 4 mm, E_Bias = +0,3 V (vs. Ag/AgCl), I_UV-light = 9.0 mW cm⁻² (2.0 W), and pH 4–10

0.2 (1.55% RSD)

≤300

Q_net = 0.0242 COD + 0.0125 (R² = 0.9985)

PEC-COD = 0.989 ThCOD (R² = 0.997, n = 24)

⁷²

WE = TiO₂/Ti, SE = Na₂SO₄, UV-type lamp

E_bias = +0.5 V (vs. SCE), t_{current stead state} = 30 s, pH 8, V = 50 µL

16 (6.8% RSD)

50–2000

i_net = 0.0085 COD—0.0596 (R² = 0.9990)

CrCOD = 1.0095 COD PEC-COD, (R² = 0.9895, n = 25)

⁹⁶

WE: Ti/TiO₂, CE: Pt_disk, SE = Na₂SO₄

Φ_{Under UV illumination} = 1.5 mm, E_bias = +0.6 V (vs. SCE), pH 6, J_Rate = 1.0 mL min⁻¹

5

50–1000

PEC-COD = 0,9345 CrCOD + 12.7726, (n = 20, R² = 0.9961)

⁴⁶

WE: TiO₂, SE = NaNO₃, CE = Pt

T_assay = 23 °C, I_Ligth = 20 mW cm⁻², E_bias = +0.3 V (vs. Ag/AgCl, pH 3–10

0.2 (1.9% RSD)

≤ 120

i_net (mA) = 0.000698 ThCOD + 0.00263 (R² = 0.9865);

PEC-COD = 1.02 COD (R² = 0.993, n = 20)

⁹⁴

WE = TiO₂/FTO, CE = Pt_wire

I_Light = 1.2 mW cm⁻² (4 W), E_Bias = 0.4 V (vs. Ag/AgCl)

1 (3.56% RSD)

≤ 130

i_net (mA) = 0.028 ThCOD + 0.024 (R² = 0.9951, n = 30)

⁴⁰

CE = Pt_foil, SE = NaNO₃ Visible light illumination

I_Light = 1.2 mW cm⁻² (230 W), E_Bias, E_Bias = 0.10 V (vs. Ag/AgCl), t_Steady = 40 s

3.0

≤ 288

Q_net = 0.0886 PEC-COD + 0.0284 (R² = 0.996)

PEC-COD = 1.0004 COD + 1.129 (R² = 0.985)

⁴²

WE: TiO₂, SE = NaNO₃

t_{Determination} = 5 min, E_{bias-choronoamperometric} = 0.4 (vs. Ag/AgCl), P_{UV-illumination} = 6.6 mW cm⁻², Φ_WE = 6 mm, C_{COD solution} = 50 mg L⁻¹

0.12 (1.5% RSD)

≤ 300

PEC-COD = 1.0027 COD—0.0365 (R² = 0.9977, n = 20)

⁴³

SE = NaSO₄

150 W Xe-lamp/30 min, pH = 6.3, I_UV-light = 2.0 mW cm⁻²

9.5 (Cl⁻_tolerance = 1400 mg·L⁻¹)

25–380

Q_net = 0.0035 CrCOD + 0.056 (R² = 0.993)

⁴⁹

CE = Pt_foil, SE = Na₂SO₄

I_UV-light = 20 mW cm⁻² (230 W)

18.3

20–280

PEC-COD = 0.9326 CrCOD + 3.1576 (R² = 0.9801)

⁵²

WE = TiO₂, CE = Pt_coil, SE = Na₂SO₄

I_light = 2.0 mW cm⁻², E_bias = 1.5 V (vs. Ag/AgCl)

8 (2.3 – 5.1% RSD)

20–250

i_net = 3.8458 ThCOD (R² = 0.9928, S/N = 3)

⁶⁸

WE = TiO₂, CE = Pt_coil, SE = Na₂SO₄

I_light = 2.0 mW cm⁻², E_bias = 1.5 V (vs. Ag/AgCl)

8 (2.3 – 5.1% RSD)

20–250

i_net = 3.8458 ThCOD (R² = 0.9928, S/N = 3)

⁶⁸

WE = 3D Pt-NPs/TNTAs/Ti, SE = Na₂SO₄, Extended-gate field-effect transistor sensor

V_Cell = 8.2 µL, P_UV-Lamp = 2 W, E_Bias = 2.5 V (vs. Ag/AgCl)

0.12 (2.7% RSD)

1.44–672

i_net = 0.0013 log (COD) - 3·10⁻⁴ (R² = 0.9744)

³⁷

WE = 3D-NPs/TNTAs, SE = Na₂SO₄

E_bias = 1.5 V (vs. Ag/AgCl), UV illumination

0.18 (3.7% RSD)

1.92–3.360

i_net = 0.000887 log (COD) – 0.000322 (S/N = 3)

⁵⁰

CE: Pt

E_Amplitude = 10 mV (vs. SCE), f = 50 kHz – 0.1 Hz, 10 steps/dec., I_Light = 50 W cm⁻²

0.05

0.20–19.9

Log (Z_relative) = -0.667 ± 0.012 log (COD) (R² = 0.9987, n = 9)

⁷⁸

WE = TiO₂, CE = Pt, SE = NaNO₃

d_{UV source - photoanode surface} = 6.5 mm, I_Light = 6.6 mW cm⁻², Th _film = 2 µm

0.2 (1.5% RSD)

1.25–576

i_net = 1.063 ThCOD + 0.0953 (R² = 0.9967)

²⁸

WE = CuS/TiO₂/ITO, CE = Pt-NPs, SE = NaNO₃

pH 3, t_assay = 5 min.

0.017 (ca. 1.5% RSD)

0.05–50

V = 0.036 logCOD + 0.438 (R² = 0.990)

⁵⁵

WE = TiO₂/g-C₃N₄/ITO, RE = Hg/Hg₂Cl₂, CE = Pt

Neutral pH, t_assay = 15 min, stability time = 30 min.

0.0084 (ca. 3% RSD)

0.025–750

RGB_blue = 86.4 COD + 110 (0.025–0.75 mg L⁻¹, R² = 0.934), RGB_blue = 0.0930 COD + 102 (<750 mg L⁻¹, R² = 0.972)

⁵⁴

WE = Te-TiO₂/Ti, CE =Pt, RE = Ag/AgCl.

E_bias = 0.6 V (vs. Ag/AgCl) at 0.1 mV s⁻¹, 84 compounds tested., UV light source.

<1 µm (ca. 1.8% RSD)

1–10 µm

ThCOD = PECOD (almost 100% accuracy)

⁴⁸