Dark Current Water Splitting Employing Ni₃TeO₆ as a Photocharged Photoelectrocatalyst

Herein, the photoelectrocatalytic and photocharging activity of a Ni₃TeO₆ (NTO-700) photoelectrocatalyst for water oxidation in alkaline medium is demonstrated and calcined at 700 °C. The photoelectrocatalytic (PEC) activity of the sample is increased upon an increase in the illumination time. With a twofold increase in photocurrent density at 1.8 V, the PEC 150 sample (having been illuminated for 150 min) attained the highest PEC activity. The synthesized material has displayed an excellent charge storage capacity in KOH and Na₂SO₄ electrolyte solutions (both 0.1 m). The chrono-amperometry measurement, subsequent to light interruption, has sustained almost 44% higher current density (even after 200 min) compared to the pure electrocatalytic baseline in a Na₂SO₄ electrolyte. The charge transfer resistance, R_ct, decreases from 633.40 to 170.40 Ω, while the charge transfer rate constant, k_ct, increases from 7.93 to 27.03 s⁻¹, as a function of illumination time. This points to fast separation of electron–hole (e⁻–h⁺) pairs and a slower recombination rate. The lower values of the charge transfer resistance and the time constant recorded for the light interrupted samples, as compared to the electrochemical sample, are attributed to the stored charge that drives water oxidation at a higher rate.