TY - JOUR

T1 - Nanostructured β-Bi2O3/Cu2O Heterojunctions Synthesized via Mechanical Milling for Visible-Light Region Photocatalysis

AU - Ayala-Ayala, Maria Teresa

AU - Gutiérrez Pérez, Aixa Ibeth

AU - Cardenas Terrazas, Paola Sarahi

AU - González-Hernández, Jesus

AU - Bahnemann, Detlef W.

AU - Muñoz-Saldaña, Juan

PY - 2025/4/22

Y1 - 2025/4/22

N2 - Visible-light-active photocatalytic heterojunctionsbased on nanostructured β-Bi2O3/Cu2O semiconductors weresuccessfully coupled by high-energy ball milling, exhibitingenhanced charge carrier separation, transfer, and reaction properties.The optical, structural, and photoelectrochemical properties ofthe catalysts and their heterojunctions were analyzed to evaluatethe coupling efficiency. The optimal stoichiometric ratio of (1 −x)β-Bi2O3/xCu2O (x = 25, 50, and 75 wt %) and the milling timesignificantly influenced the optical properties, including photoluminescence(PL). A notable decrease in PL intensity wasobserved for the heterojunction with x = 25%, compared to thatof the single semiconductors. This effect was further enhanced withincreasing milling time, which is attributed to the mechanicalenergy input. The formation of nanosized mixed-phase transition heterojunctions was confirmed by scanning electron microscopy(SEM), high-resolution transmission electron microscopy (HRTEM), and energy-dispersive spectroscopy (EDS). Structuralcharacterization revealed increased lattice parameters and reduced crystallite size due to mechanical milling. Milling-inducedstructural deformations led to decreased PL intensity and band gap energy. Photocatalytic efficiency was the highest forheterojunctions prepared with shorter milling times; longer milling times introduced structural defects that reduced photocatalyticperformance. Flat band potential (EFB) analysis identified a p−n junction with staggered band edge alignment. The heterojunction,which was milled for 60 min, exhibited an absorption range extending up to 1.84 eV. Notably, the 75β-Bi2O3/25Cu2O sample milledfor 5 min achieved 98% photocatalytic efficiency under visible light irradiation. Mechanical milling is a simple, inexpensive, one-stepprocess for fabricating nano-sized heterojunctions with well-mixed interfaces that enhance charge carrier separation. While structuraldefects are detrimental in excess, they can enhance photocatalytic activity at optimal concentrations.

AB - Visible-light-active photocatalytic heterojunctionsbased on nanostructured β-Bi2O3/Cu2O semiconductors weresuccessfully coupled by high-energy ball milling, exhibitingenhanced charge carrier separation, transfer, and reaction properties.The optical, structural, and photoelectrochemical properties ofthe catalysts and their heterojunctions were analyzed to evaluatethe coupling efficiency. The optimal stoichiometric ratio of (1 −x)β-Bi2O3/xCu2O (x = 25, 50, and 75 wt %) and the milling timesignificantly influenced the optical properties, including photoluminescence(PL). A notable decrease in PL intensity wasobserved for the heterojunction with x = 25%, compared to thatof the single semiconductors. This effect was further enhanced withincreasing milling time, which is attributed to the mechanicalenergy input. The formation of nanosized mixed-phase transition heterojunctions was confirmed by scanning electron microscopy(SEM), high-resolution transmission electron microscopy (HRTEM), and energy-dispersive spectroscopy (EDS). Structuralcharacterization revealed increased lattice parameters and reduced crystallite size due to mechanical milling. Milling-inducedstructural deformations led to decreased PL intensity and band gap energy. Photocatalytic efficiency was the highest forheterojunctions prepared with shorter milling times; longer milling times introduced structural defects that reduced photocatalyticperformance. Flat band potential (EFB) analysis identified a p−n junction with staggered band edge alignment. The heterojunction,which was milled for 60 min, exhibited an absorption range extending up to 1.84 eV. Notably, the 75β-Bi2O3/25Cu2O sample milledfor 5 min achieved 98% photocatalytic efficiency under visible light irradiation. Mechanical milling is a simple, inexpensive, one-stepprocess for fabricating nano-sized heterojunctions with well-mixed interfaces that enhance charge carrier separation. While structuraldefects are detrimental in excess, they can enhance photocatalytic activity at optimal concentrations.

KW - bismuth oxide

KW - flat band potential

KW - heterojunction engineering

KW - mechanoactive

KW - metal oxide semiconductor

KW - visible-light photocatalyst

UR - https://www.mendeley.com/catalogue/42ba99b6-4591-3717-91de-a6f8b06025d8/

U2 - 10.1021/acsanm.4c07108

DO - 10.1021/acsanm.4c07108

M3 - Article

VL - 8

SP - 8663

EP - 8675

JO - ACS Applied Nano Materials

JF - ACS Applied Nano Materials

SN - 2574-0970

IS - 17

ER -