Cascade electron transfer in ternary CuO/α-Fe2O3/γ-Al2O3 nanocomposite as an effective visible photocatalyst

Abstract

Highly efficient ternary heterojunction of CuO/α-Fe2O3/γ-Al2O3 was effectively fabricated by a facile and cost effective chemical route. The structural, chemical composition, morphology, optical and photocatalytic properties of as-prepared CuO/α-Fe2O3/γ-Al2O3 photo catalyst were compared to pristine and binary samples by various characterization. Existence of all the dominant peaks of CuO, α-Fe2O3 and γ-Al2O3 are noticeable in XRD spectrum of CuO/α-Fe2O3/γ-Al2O3 ternary photo catalyst which confirms the successful formation of the photocatalyst. SEM and HRTEM results revealed the spherical shape CuO nanoparticles with distorted α-Fe2O3 agglomerated plates which led to complete diffusion with γ-Al2O3. The band gap of ternary nanocomposite was found to be 1.9 eV elucidated by UV-DRS. Brunauer-Emmett-Teller (BET) analysis showed that as-fabricated ternary CuO/α-Fe2O3/γ-Al2O3 nanocomposite exhibited the porous structure with large surface area and small pore volume as compared to pristine γ-Al2O3.due to the unique ternary nanocomposite structure and synergistic effect among various components. The photocatalytic activity was examined by monitoring the deterioration of methyl orange under simulated solar light irradiation. CuO/α-Fe2O3/γ-Al2O3 exhibited superior photocatalytic efficacy as compared to CuO/γ-Al2O3 and α-Fe2O3/γ-Al2O3 binary and pure oxides of γ-Al2O3, CuO and α-Fe2O3. The marvelous photocatalytic activity of CuO/α-Fe2O3/γ-Al2O3 ternary nanocomposite samples can be ascribed to their close contact, strong interfacial hybridization and proficient charge transfer capacity. The electrochemical studies such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were carried out to explore the charge transfer behavior and support the high photo activity of ternary nanocomposite CuO/α-Fe2O3/γ-Al2O3. LSV measurements manifested that CuO/α-Fe2O3/γ-Al2O3 exhibited 4.3 folds higher current density than bare γ-Al2O3 which confirmed the faster electron transfer from CuO to γ-Al2O3 via mediated α-Fe2O3 through the interfacial potential gradient in conduction band. Cyclic voltammetry (CV) results showed that pair of anodic and cathodic peaks in CuO/α-Fe2O3/γ-Al2O3 appeared which affirm the efficient increase in photo-induced e−/h+ separation and suppress recombination rate of electron-hole pair. This work demonstrated that CuO/α-Fe2O3/γ-Al2O3 ternary nanocomposite is found to be a promising candidate as an efficient adsorbent for organic dye removal from waste water.