Pr doped BiFeO3 hollow nanofibers via electrospinning method as a formaldehyde sensor

Boosting Electrocatalytic Oxygen Evolution: Superhydrophilic/Superaerophobic Hierarchical Nanoneedle/Microflower Arrays of CexCo3–xO4 with Oxygen Vacancies

“…The negative shift of the Co 2p 3/2 peak and positive shift of the U2 peak for Ce 3d suggest that Ce atoms might interact electrostatically with the surrounding Co atoms and the electrons migrated from Ce to Co atom, where Co 3+ was reduced to Co 2+ followed by an increase of oxygen vacancies . In Figures e and S6, the XPS spectra of O 1s directly show the changes in oxygen vacancies (O V ) at 532.3 eV. , Among these samples, Ce 0.12 Co 2.88 O 4 had the highest relative concentration ratio of O V (37.05%) (Figure f). Notably, higher Ce content in Ce 0.24 Co 2.76 O 4 and Ce 0.48 Co 2.52 O 4 did not generate more oxygen vacancies, probably because more Ce addition tends to form CeO 2 species, which is reflected in the XRD patterns (Figures a and S4).…”

“…A lot of alternative OER catalysts based on earth-abundant metals (e.g., Fe, Co, Ni, and Mn), including phosphates, − chalcogenides, − nitrides, , and boride, have been brought up, but most of the above catalysts are thermodynamically less stable than metal oxides in strongly oxidative environments, which are usually reconstructed to form the real active species of metal oxides/(oxy)­hydroxides during the OER measurement. ,, Among metal oxides, Co 3 O 4 has attracted tremendous attention as an OER catalyst for its excellent catalytic activity and electrochemical durability in alkaline electrolytes, but its catalytic performance is inhibited by low active site exposure, poor conductivity, and unsuited adsorption strength for intermediates. − Several strategies have been utilized to optimize the catalytic activity of metal oxides, such as incorporating foreign elements and oxygen defects to modulate electronic structure − and regulating the morphology of catalysts with larger surface area to fully expose active sites. − Recently, rare-earth elements (like Ce, Pr, and La) have made great progress in the fields of sensors, , phosphors, and catalysts. − Among rare-earth elements, Ce has unique oxophilic properties, which can modify the local electronic environment and facilitate the subsequent series of oxygen-containing intermediate adsorption and reaction conversion to accelerate the generation of oxygen. , Benefiting from the flexible transition between Ce 3+ and Ce 4+ , Ce can modify local chemical binding to increase oxygen vacancy concentration for improving the electrical conductivity of metal oxides. , In addition, Ce ion can be regarded as a hard Lewis acid for the special property of easy oxyphilic coordination with flexible and high coordination number, which makes it easy to bond with some hard oxygen ligands (like OH – ). Therefore, Ce ion can be regarded as a buffer to hinder the attack from alkaline solution, playing a role in regulating the crystal growth and overall morphology of metal oxides. ,, …”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…Materials with nanofibers structures were also attested their sensing ability to HCHO vapor. Ag-doped LaFeO 3 nanofibers, Co 3 O 4 -ZnO core-shell nanofibers, WO 3 /ZnWO 4 —1D nanofibers, and Pr-doped BiFeO 3 /hollow nanofibers were synthesized by electrospinning method with the combination of calcination tactic and utilized in HCHO detection at 190–230 °C [ 253 , 254 , 255 , 256 ]. As shown in Table 3 , WO 3 /ZnWO 4 —1D hetrostructured nanofibers are found to be a good candidate in terms of the sensor response (R a /R g = 44.5 for 5 ppm at 220 °C; response/recovery time = 12 s/14 s) with a LOD of 1 ppm [ 255 ].…”

Perovskite@Graphene Nanohybrids for Breath Analysis: A Proof-of-Concept

“…In this regard, Y. Tie and collaborators demonstrated that by doping BiFeO 3 hollow nanofibers with Pr, the optimum operating temperature for detecting some gases such as formaldehyde can be lowered to some extent [75].…”