Rare-earth (Nd and Eu) induced structural transformation and optical properties of brownmillerite-type Sr2ScGaO5 oxide

Structure‐property Relationship of Double Perovskite Oxide towards Trifunctional Electrocatalytic Activity: Strategy for Designing and Development

“…The crystal structures of DP ( A 2 BB′ O 6 ) are originated from the single perovskite structure with partial substitution of various cations that accommodates 80–90 % metal ions in the periodic table. Commonly, the DP structures where the volume may enhance (in case of B ‐site ordered or disordered site) compared to the simple cubic perovskite structure [72–73] . Depending upon the doping or substitution with aliovalent cations at A ‐ and B ‐sites in simple perovskite, resulting the creation of A ‐ and B ‐site order‐disorder double perovskite with general formula of AA ′ B 2 O 6 and A 2 BB ′O 6 , respectively (Scheme 2).…”

“…Depending upon the doping or substitution with aliovalent cations at A ‐ and B ‐sites in simple perovskite, resulting the creation of A ‐ and B ‐site order‐disorder double perovskite with general formula of AA ′ B 2 O 6 and A 2 BB ′O 6 , respectively (Scheme 2). [51–53,74–75] Typically, A ‐and A ′‐site is consists of alkaline‐earth metal or rare‐earth metal ions (e. g., Ca, Sr, Ba, La, Pr, Sm) whereas B ‐and B ′‐site is comprises of variable valence 3 d –3 d , 3 d –4 d or 3 d –5 d mixed metal cations (e. g., Mn, Ni, Fe, Co, Ti, Ru, Os) [51–53,58–60,72,76–79] . Further, in most of the DPs structure the smaller size B ‐site cations are surrounded by 6 oxygen anions to form B O 6 octahedral coordination while the A ‐site cations can exhibits large size 12‐fold coordination sites adjacent with eight B O 6 octahedra to form cub‐octahedral cages [51–53,72] .…”

“…It is often noted that most of the DP structures synthesized through Solid‐state synthesis techniques preferably at high temperature formed bulk and agglomerated particles while low‐temperature sintering using sol‐gel methods which followed the precise controlled techniques that normally produces nanostructure of DP oxides [51–55,85–86] . Moreover in DP structure, the A ‐site elements have a significant role to regulate the thermodynamic stability whereas the B ‐site elements evaluate the various exciting electronic properties i. e., magnetism, dielectric as well as potential energy related applications [47,51–58,72,78–80,82–86] …”

“…[51][52][53][54][55][85][86] Moreover in DP structure, the A-site elements have a significant role to regulate the thermodynamic stability whereas the B-site elements evaluate the various exciting electronic properties i. e., magnetism, dielectric as well as potential energy related applications. [47,[51][52][53][54][55][56][57][58]72,[78][79][80][82][83][84][85][86]…”

“…Moreover, the arrangement of e g 2 state of (Fe 3 + ) and e g 0 state of (Ru 5 + ) may also exhibits superior trifunctional activity of CFRO catalyst compared to the well-known e g 1 system of B-site metal ions though more investigation is still required to establish and understand the exact role of e g electrons in the trifunctional electrocatalytic performances of such oxide family. [89] With our continuous effort to discover novel multifunctional DP structures, [51][52][53][58][59][60]72,76,85] further we have synthesized two new phase pure DP materials namely as Ca 2 ScRuO 6 (CSRO) and CaSrScRuO 6 (CSSRO) to examined the role of A-site doping as well as the effect of 3d metal ions at B-site by fixing of 4d element in electrocatalytic OER/ORR/HER studies. [90] The OER LSV performance of CSRO and CSSRO catalysts in 1 M KOH electrolyte showed the overpotential of 353 mV and 323 mV @ 10 mA cm À 2 including Tafel slope values of 105 mV dec À 1 (CSRO) and 98 mV dec À 1 (CSSRO), indicating their excellent OER activity (Figure 3b and 3d).…”