All‐In‐One Perovskite Catalyst: Smart Controls of Architecture and Composition toward Enhanced Oxygen/Hydrogen Evolution Reactions

Abstract

catalysts with low-cost and earth-abundant materials. [5][6][7][8][9][10] In terms of achieving the best performances, the HER is usually carried out in an acidic environment while the OER in an alkaline condition. Nevertheless, practical utilization of these electrodes in an integrated electrolysis device has been hindered since the HER and OER catalysts usually require very different pH values in order to produce long lifetimes and high activities. In this context, a bifunctional electrocatalyst with high activities for both the OER and HER in an identical condition is desired. [10][11][12][13] Most state-of-the-art water splitting catalyst researches have been focused on the development of nonprecious metal catalysts that are competitive to precious metals. [5][6][7][8][9][10][14][15][16][17][18] As a result, perovskites are being spotlighted as promising candidates due to their favorable compositional flexibility and good stability in a wide range of electrochemical window, thus enabling easy modification of their catalytic properties. Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) has been introduced as an excellent OER catalyst, whose catalytic activity for water oxidation is one order higher than that of IrO 2 in alkaline conditions. [16][17][18] Furthermore, Xu et al. proved BSCF is capable of catalyzing HER in alkaline conditions. [15] They also found that its HER catalytic performance and durability can be drastically improved via proper A-site Pr-doping. Nevertheless, surface amorphous phases in Pr-doped BSCF were still found after the durability test. It was reported that a smaller size mismatch between the host and dopant cations in the A-site has a remarkable effect on rationalizing the stabilities and activities of cubic BSCF. [19,20] Consequently, we predict that the La-doped BSCF would possess better robustness than Pr-doped BSCF (note that the sequence of ion radiuses is Ca 2+ <Pr 3+ <La 3+ <Sr 2+ <Ba 2+ ). Additionally, small amounts of Ca-doping can bring a significant increase in the corrosion resistance of perovskite because Ca(OH) 2 and CaCO 3 are easier to decompose than Ba (Sr) compounds. In addition to the intrinsic properties, we also noted that a higher quantity of active areas and porosities, as well as fast electron conduction kinetics, is among the necessities for electrochemical reactions. [21][22][23][24] In this article, we presented excellent catalytic performance and stability toward overall water splitting via La/Ca co-doping A conventional water electrolyzer consists of two electrodes, each of which is embedded with a costly and rare electrocatalyst, typically IrO 2 /C for oxygen evolution reaction (OER) and Pt/C for hydrogen evolution reaction (HER), respectively. HER and OER electrocatalysts usually require very different pH values to keep them stable and active. Thus, the development of earth-abundant nonprecious metal catalysts for both HER and OER is of great importance to practical applications. This work reports the results of integrated water electrolysis using the hybrids ...

Evaluation of A-Site Ba2+-Deficient Ba1−xCo0.4Fe0.4Zr0.1Y0.1O3−δ Oxides as Electrocatalysts fo

“…Moreover, the Tafel plots depicted in Figure 5(b) were calculated to get an insight into the HER kinetic processes of the catalysts. The Pt/C catalyst shows a Tafel slope of 31.2 mV dec −1 , which is consistent with the reported values [11, 26]. The Tafel slope of Ba 0.95 CFZY is 80.4 mV dec −1 , which is lower than those of Ba 0.99 CFZY (85.9 mV dec −1 ), BaCFZY (87.5 mV dec −1 ), and BSCF (92.0 mV dec −1 ).…”

Identifying the Activation Mechanism and Boosting Electrocatalytic Activity of Layered Perovskite Ruthenate

“…ABO 3 perovskites have been widely applied as functional electrode materials in catalytic system with promising performance . In addition, remarkable advancements in the catalytic mechanism regarding the water splitting system for perovskite have been achieved . Latest research uncovered the nature of transition‐metal ion in B‐site of perovskite partly governs the intrinsic catalytic activity, thus the selection of B‐site ion is of paramount importance .…”

Recent Advances in Novel Nanostructuring Methods of Perovskite Electrocatalysts for Energy‐Related Applications

“…For instance, niobium‐doped perovskites, which are typically synthesized from solid‐state reaction using niobium pentoxide, can be fabricated by electrospinning using ammonium niobite oxalate hydrate (C 4 H 4 NNbO 9 · x H 2 O) as the metal source . Very recently, Hua et al reported the electrospinning synthesis of a septenary perovskite oxide, La 0.5 (Ba 0.4 Sr 0.4 Ca 0.2 ) 0.5 Co 0.8 Fe 0.2 O 3− δ , which further showcases the advantage of electrospinning in manufacturing multicomponent perovskites.…”

“…In addition, constructing perovskite/nanocarbon hybrids can influence the electron transfer and reaction kinetics during the OER and HER, which should be a useful way to enhance the dual functionality of perovskite electrocatalysts. One recent example was showcased by Hua et al, who attached electrospun La 0.5 (Ba 0.4 Sr 0.4 Ca 0.2 ) 0.5 Co 0.8 Fe 0.2 O 3− δ (L‐0.5) perovskite nanorods to RGO nanosheets via a simple ultrasound treatment . The assembly of L‐0.5 and RGO boosted the HER/OER reactivity by collective effects, further affording enhanced overall water‐splitting performance (1.76 V @ 50 mA cm −2 geo ) close to that of the Pt/C–IrO 2 /C couple.…”

“…Recent years have seen a veritable explosion of research activity targeting the synthesis of 1D perovskite structures, such as nanotubes, [128][129][130][131] nanofibers, [61,[132][133][134][135] and nanorods. [51,[136][137][138] A common setup for electrospinning is shown in Figure 8a, which is composed of a high-voltage power supply, a syringe with a metallic needle, and a grounded conductive collector. A detailed working principle of the electrospinning technique is available elsewhere.…”