Abstract:Double perovskites have emerged as efficient candidates for catalyzing the electrochemical oxygen evolution reaction (OER). Smart control of the composition of a B‐site ordered double perovskite can lead to improved catalytic performance. By adopting a facile co‐doping strategy, the OER‐active elements are simultaneously introduced into the B‐site and B′‐site of a B‐site‐ordered double perovskite (A2BB′O6), leading to an enhancement of the exposed reactive sites and an optimum surface chemical state. As a resu… Show more
“…All the powders were synthesized by a facile sol‐gel method, involving thermal‐induced self‐assembly at high temperature . The as‐synthesized material structure was initially investigated using laboratory‐based XRD (Figure S1), which revealed a hybrid DP and SP oxide composition as shown by the reflection of at ≈19.5° arising from B‐site ordering .…”
Section: Resultsmentioning
confidence: 99%
“…The single/double perovskite (SP/DP) system with the nominal composition Sr 2 Fe 0.2 Co 0.8 Mo 0.65 Ni 0.35 O 6−δ , double perovskite Sr 2 Fe 0.8 Co 0.2 Mo 0.65 Ni 0.35 O 6−δ , and single perovskite SrFe 0.5 Co 0.5 O 3−δ were synthesized by a sol‐gel method . Taking Sr 2 Fe 0.2 Co 0.8 Mo 0.65 Ni 0.35 O 6−δ (10 mmol) as an example, Sr(NO 3 ) 2 (4.2326 g), Fe(NO 3 ) 3 ⋅9 H 2 O (3.2320 g), Co(NO 3 ) 2 ⋅6 H 2 O (1.7462 g), (NH 4 )Mo 7 O 24 ⋅4 H 2 O (1.1476 g), and Ni(NO 3 ) 2 ⋅6 H 2 O (1.4540 g) (all analytical grade from Sinopharm Chemical Reagent Co., Ltd.) were dissolved in deionized water with the assistance of citric acid (CA, 16.8 g) and C 10 H 16 N 2 O 8 (EDTA, 11.6 g).…”
Section: Methodsmentioning
confidence: 97%
“…Xu and co‐workers reported that the partial substitution of Fe in CoAl 2 O 4 allowed the control of surface reconstruction to form active oxyhydroxides under OER conditions, improving catalytic performance . Additionally, high‐valence 3 d‐transition metal ions incorporated into metal oxides are known to achieve a high reactivity towards water oxidation, which have been confirmed by some highly covalent oxides with lattice oxygen involved …”
Section: Introductionmentioning
confidence: 97%
“…Among many candidate materials, single perovskites of ABO 3 ‐type where A and B are commonly rare‐earth and transition‐metal elements, respectively, are regarded as promising OER electrocatalysts owing to low cost, rich composition, flexible crystal structure, and tunable lattice and surface defects . The OER activity of such perovskites can be boosted through tailoring the crystal, defect, or electronic structure.…”
Perovskite‐based oxides have emerged as promising oxygen evolution reaction (OER) electrocatalysts. The performance is closely related to the lattice, electronic, and defect structure of the oxides, which determine surface and bulk properties and consequent catalytic activity and durability. Further, interfacial interactions between phases in a nanocomposite may affect bulk transportation and surface adsorption properties in a similar manner to phase doping except without solubility limits. Herein, we report the development of a single/double perovskite nanohybrid with limited surface self‐reconstruction capability as an OER electrocatalyst. Such superior performance arises from a structure that maintains high crystallinity post OER catalysis, in addition to forming an amorphous layer following the self‐reconstruction of a single perovskite structure during the OER process. In situ X‐ray absorption near edge structure spectroscopy and high‐resolution synchrotron‐based X‐ray diffraction reveal an amorphization process in the hybrid single/double perovskite oxide system that is limited in comparison to single perovskite amorphization, ensuring high catalytic activity.
“…All the powders were synthesized by a facile sol‐gel method, involving thermal‐induced self‐assembly at high temperature . The as‐synthesized material structure was initially investigated using laboratory‐based XRD (Figure S1), which revealed a hybrid DP and SP oxide composition as shown by the reflection of at ≈19.5° arising from B‐site ordering .…”
Section: Resultsmentioning
confidence: 99%
“…The single/double perovskite (SP/DP) system with the nominal composition Sr 2 Fe 0.2 Co 0.8 Mo 0.65 Ni 0.35 O 6−δ , double perovskite Sr 2 Fe 0.8 Co 0.2 Mo 0.65 Ni 0.35 O 6−δ , and single perovskite SrFe 0.5 Co 0.5 O 3−δ were synthesized by a sol‐gel method . Taking Sr 2 Fe 0.2 Co 0.8 Mo 0.65 Ni 0.35 O 6−δ (10 mmol) as an example, Sr(NO 3 ) 2 (4.2326 g), Fe(NO 3 ) 3 ⋅9 H 2 O (3.2320 g), Co(NO 3 ) 2 ⋅6 H 2 O (1.7462 g), (NH 4 )Mo 7 O 24 ⋅4 H 2 O (1.1476 g), and Ni(NO 3 ) 2 ⋅6 H 2 O (1.4540 g) (all analytical grade from Sinopharm Chemical Reagent Co., Ltd.) were dissolved in deionized water with the assistance of citric acid (CA, 16.8 g) and C 10 H 16 N 2 O 8 (EDTA, 11.6 g).…”
Section: Methodsmentioning
confidence: 97%
“…Xu and co‐workers reported that the partial substitution of Fe in CoAl 2 O 4 allowed the control of surface reconstruction to form active oxyhydroxides under OER conditions, improving catalytic performance . Additionally, high‐valence 3 d‐transition metal ions incorporated into metal oxides are known to achieve a high reactivity towards water oxidation, which have been confirmed by some highly covalent oxides with lattice oxygen involved …”
Section: Introductionmentioning
confidence: 97%
“…Among many candidate materials, single perovskites of ABO 3 ‐type where A and B are commonly rare‐earth and transition‐metal elements, respectively, are regarded as promising OER electrocatalysts owing to low cost, rich composition, flexible crystal structure, and tunable lattice and surface defects . The OER activity of such perovskites can be boosted through tailoring the crystal, defect, or electronic structure.…”
Perovskite‐based oxides have emerged as promising oxygen evolution reaction (OER) electrocatalysts. The performance is closely related to the lattice, electronic, and defect structure of the oxides, which determine surface and bulk properties and consequent catalytic activity and durability. Further, interfacial interactions between phases in a nanocomposite may affect bulk transportation and surface adsorption properties in a similar manner to phase doping except without solubility limits. Herein, we report the development of a single/double perovskite nanohybrid with limited surface self‐reconstruction capability as an OER electrocatalyst. Such superior performance arises from a structure that maintains high crystallinity post OER catalysis, in addition to forming an amorphous layer following the self‐reconstruction of a single perovskite structure during the OER process. In situ X‐ray absorption near edge structure spectroscopy and high‐resolution synchrotron‐based X‐ray diffraction reveal an amorphization process in the hybrid single/double perovskite oxide system that is limited in comparison to single perovskite amorphization, ensuring high catalytic activity.
“…[ 9a,28b ] In addition, Co ions have rich and tunable redox behaviors, including valence states (Co 2+ , Co 3+ , and Co 4+ ) and spin states (low spin, intermediate spin, and high spin) that provide wide opportunities to design and construct desired properties. [ 127 ] A number of excellent reviews of Co‐based electrocatalysts are available. [ 10a,b,28b ] In this section, we briefly emphasize the application of high‐valence Co sites in designing excellent electrocatalysts for water splitting ( Table 2 ).…”
Section: Advanced Water‐splitting Electrocatalysts With High‐valence mentioning
Electrochemical water splitting is a critical energy conversion process for producing clean and sustainable hydrogen; this process relies on low‐cost, highly active, and durable oxygen evolution reaction/hydrogen evolution reaction electrocatalysts. Metal cations (including transition metal and noble metal cations), particularly high‐valence metal cations that show high catalytic activity and can serve as the main active sites in electrochemical processes, have received special attention for developing advanced electrocatalysts. In this review, heterogenous electrocatalyst design strategies based on high‐valence metal sites are presented, and associated materials designed for water splitting are summarized. In the discussion, emphasis is given to high‐valence metal sites combined with the modulation of the phase/electronic/defect structure and strategies of performance improvement. Specifically, the importance of using advanced in situ and operando techniques to track the real high‐valence metal‐based active sites during the electrochemical process is highlighted. Remaining challenges and future research directions are also proposed. It is expected that this comprehensive discussion of electrocatalysts containing high‐valence metal sites can be instructive to further explore advanced electrocatalysts for water splitting and other energy‐related reactions.
Ultrathin perovskite oxides with tailored crystal structures are promising catalysts for oxygen evolution reaction (OER) owing to their high intrinsic catalytic activity and large exposed active surface area. However, the synthesis of phase-controllable perovskite oxide nanosheets with thickness down to a few nanometers remains a challenge since the formation of a perovskite phase often requires long-time calcination at high temperatures. Here, a salt-templated strategy for fabrication of atomically thin perovskite oxide of LaMnO 3 with tailored phase structure for highly active OER catalysts is reported. The orthorhombic structure of LaMnO 3 nanosheets demonstrates much higher electrochemical activity than the tetragonal or hexagonal phase and the benchmark IrO 2 catalyst, exhibiting extremely small onset overpotential (≈70 mV) and a low overpotential (≈324 mV at 10 mA cm 2 disk − ) in alkaline solution. The remarkable OER activity of this catalyst is attributed to the desired surface binding energetics (or the unique electronic structures) inherent to the orthorhombic phase, as predicted by density functional theory calculations and confirmed by experimental measurements. Further, it is believed that this study paves a new path toward rational the design of perovskite oxide nanosheets with desired phase structures for many applications.
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