Effect of doping on the morphology of cerium molybdate: A mechanistic approach towards efficient energy storage and sustainable environmental mitigation through heterogeneous photocatalysis

Abstract

In this paper, we describe the synthesis of cerium molybdate (Ce2(MoO4)3) and different compositions of Bi-doped cerium molybdate (Ce2-xBix(MoO4)3) where x = 0.01, 0.03, 0.05, 0.07, and 0.09, through simple co-precipitation method. The synthesized materials were optically, structurally, and morphologically characterized by various sophisticated techniques, including UV–visible, FTIR, Raman, PXRD, BET, and SEM-EDX. Upon addition of bismuth, the optical band gaps are reduced from 3.35 eV (Ce2(MoO4)3) to 2.83 eV Ce1.93Bi0.07(MoO4)3. The charge storage potential and AC conductivity of the synthesized materials were investigated through dielectric studies where the dielectric constant increased by increasing dopant concentration up to 7 %. At 20 Hz, Ce1.93Bi0.07(MoO4)3 showed a significantly greater dielectric constant (3.597 × 106) compared to undoped Ce2(MoO4)3 (3.262 × 105). Similarly, the AC conductivity of Ce1.93Bi0.07(MoO4)3 increased up to 4.758 S m−1 compared to the undoped Ce2(MoO4)3 (2.270 S m−1) at 20 MHz. The photocatalytic efficiency was investigated against diclofenac potassium, which also considerably improved by increasing bismuth content. The maximum photodegradation efficiency of 87.9 % was observed for Ce1.93Bi0.07(MoO4)3 in 180 min under UV light irradiation at optimized conditions (pH = 4, catalyst dosage = 20 mg, and initial concentration of drug = 5 mg L−1). The photocatalytic reaction followed pseudo-first-order kinetics with a rate constant of 0.0108 min−1 with stability up to five successive runs of photocatalytic activity indicating its good recyclability. These findings suggest that Bi-doped cerium molybdate could be used as a promising material for photocatalysis and energy storage devices.