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The Cu-LFO/Ni-LFO homojunction reduces the defects caused by the lattice mismatch at the interface and the recombination of photogenerated carriers. In addition, the relative positions of the Fermi energy levels of Cu-LFO and Ni-LFO are adjusted by ion doping to achieve the synergistic enhancement of photogenerated carrier separation by the triple synergy of applied voltage, energy band potential and built-in electric field. Meanwhile, Ni-LFO modulates the adsorption and desorption of water molecules and reduction reaction intermediates to accelerate the reaction kinetics at the semiconductor-electrolyte interface. [Display omitted] • Modulation of built-in electric field direction by metal ion doping; • Synergistic enhancement of photogenerated carrier separation; • Reduction of interfacial defects and photogenerated carrier recombination; • Ni-LFO served as co-catalyst-like agent to optimize HER reaction kinetics. LaFeO 3 (LFO), a typical p-type semiconductor, is considered as a promising material for photoelectric conversion because of its flexible composition and structure. However, its severe photogenerated carrier recombination and surface reaction kinetic hysteresis greatly limit its application in photoelectrochemistry (PEC) water splitting. Here, for the first time, a LFO p-p-type homojunction (Cu-LFO/Ni-LFO) formed by Cu-doped LFO and Ni-doped LFO is reported. Experimental investigation and density functional theory (DFT) calculations reveal that Cu and Ni doping forms a built-in electric field directed from Ni-LFO to Cu-LFO, which effectively improves the carrier separation and transport efficiency. The comparable crystal structure at the interface minimizes the photogenerated carrier recombination due to the interface lattice mismatch. In addition, Ni-LFO in contact with the electrolyte served as a co-catalyst like role in this PEC system, improving the kinetic properties of the surface reaction significantly by optimizing the adsorption and desorption of H 2 O molecules and HER reaction intermediates on the Fe in the active center whilst significantly reducing the energy barrier. As a result, the photocurrent density of the Cu-LFO/Ni-LFO photocathode reaches 5.94 mA cm2, which is 11 times higher than that of Cu-LFO and surpasses all LFO-based photocathodes reported so far. The LFO-based p-p homo-junction synthesized in this work is instructive for improving the carrier separation efficiency and surface reaction kinetics of LFO. [ABSTRACT FROM AUTHOR]

[Display omitted] • LFOBC catalyst exhibited 94.6 % TC removal in 60 min. • Fe3+/Fe2+, Cu2+/Cu+ dual redox centers played a key role in TC removal. • Identified •OH radicals as the major active species in the photo-Fenton process. • Degradation pathway and mechanism are explored. The rising number of contaminants released into the environment and the inadequacies of traditional wastewater treatment techniques have led to the demand for enhanced oxidation technologies like photo-Fenton. In this study, bimetal co-doped lanthanum orthoferrite (Bi x La 1-x Cu y Fe 1-y O 3 (x = 0, 0.01, 0.05, 0.1; y = 0, 0.01, 0.05, 0.1, 0.15)) based photo-Fenton catalysts with the in-built redox couples Fe3+/Fe2+, Cu2+/Cu+ and oxygen vacancies have been successfully synthesised via a facile one-pot solution combustion route. Systematic studies show that the Bi 0. 05 La 0. 95 Cu 0.1 Fe 0. 9 O 3 (LFOBC) exhibits an optimal photo-Fenton degradation rate of 0.0497/min for Tetracycline (TC) removal, being ∼ 1.8 and ∼ 6.2 times greater than Bi 0.05 La 0.95 FeO 3 (LFOB) and pristine LaFeO 3 (LFO) respectively. DFT analysis confirmed the better adsorption and dissociation of H 2 O 2 on a bimetal co-doped catalyst and identified the electron density difference in LFOBC, which can induce the H 2 O 2 dissociation. A detailed investigation of various influencing reaction parameters is explored. The degradation pathway for the LFOBC catalyst with the toxicological characteristics of each intermediate is analysed. This study presents the Bi 0.05 La 0.95 Cu 0.1 Fe 0.9 O 3 as a potential photocatalyst for enhanced photo-Fenton degradation with excellent efficiency observed for the degradation of various harmful pollutants for environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • LFTCO absorbent was created by introducing Ti and Co transition metals in B sites of perovskite oxides LaFeO 3. • Ferromagnetic LFTCO exhibits a methyl blue adsorption capacity (q max) of 2131 mg/g. • The electrostatic force and chelation linkage were the main driving forces in the chemisorption of MB on LFTCO. • A novel dual-doped method gives LFTCO exceptional adsorption capabilities and Fenton-based regeneration potential. Creating adsorbents that exhibit high selectivity towards pollutants, can be readily regenerated, and maintain high stability, remains a crucial challenge in water treatment technology. Herein, we present a magnetically and chemically recoverable absorbent based on Ti and Co co-substituted LaFeO 3 (La 0.9 Fe 0.55 Ti 0.3 Co 0.15 O 3 , LFTCO) with significantly enhanced adsorption properties. Notably, LFTCO exhibits a methyl blue adsorption capacity (q max) of 2131 mg/g, setting a new record among perovskite oxides, due to the increased surface oxygen vacancy with the dual doping strategy. The selected dual-dopant consists of Fenton active Co and spin-state interactive Ti, which allows creating more oxygen vacancy and simultaneously facilitating pragmatic regeneration of the adsorbent. The new LFTCO exhibits significantly enhanced ferromagnetism (M = 7.27 emu/g), enabling rapid magnetic separation from water and subsequent Fenton-based regeneration step. We also reveal that the anchored configuration of SO 3 -defect site, through density functional theory (DFT) calculation, as the most favorable site for the adsorption process. These findings provide a pathway to creating high-performance adsorbents and shed light on the mechanistic understanding of LFTCO's enhanced adsorption properties. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The highly efficient LaFeO 3 perovskite oxides were synthesized. • DFT calculations are conducted for PMS adsorption and electron transfer. • ATR-FTIR was used for in situ characterization of LFO surface during catalytic reaction. • Activation mechanisms of PMS by LFO were proposed. • Diclofenac degradation pathways were presented. Abstract A perovskite oxide, LaFeO 3 (LFO), was synthesized and evaluated as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for the oxidative degradation of diclofenac (DCF), a non-steroidal anti-inflammatory drug. It was observed that the catalytic activity of LFO was much higher than that of Fe 2 O 3. LFO catalyzed PMS to degrade DCF with a turnover frequency (2.02 × 10−3 min−1) which is 17-fold higher than that of Fe 2 O 3. Both sulfate and hydroxyl radicals were identified during LFO-activated PMS process by electron spin resonance (ESR). Radical competitive reactions indicate sulfate radicals played a major role in DCF degradation by LFO/PMS process. The PMS decomposition can be attributed to the formation of an inner-sphere complexation between the Fe (III) sites on LFO surface and PMS. Theoretical calculations illustrated the strong interaction between PMS and Fe (III) and electron transfer from PMS to Fe (III). Hydrogen temperature-programmed reduction (H 2 -TPR) indicates that the LFO perovskite oxide is capable of facilitating an easier reduction of Fe (III) to mediate a redox process. Oxygen temperature-programmed desorption (O 2 -TPD) suggests much more oxygen vacancies exist in LFO than in Fe 2 O 3. Oxygen vacancies are favorable for the formation of chemical bond between Fe (III) and PMS and the activation of PMS. In situ ATR-FTIR analysis of LFO surface during PMS decomposition implies Fe (III)–Fe(II)–Fe (III) redox cycle was believed to account for the generation of sulfate radical. The intermediates generated during DCF degradation were identified and the possible degradation pathways were advanced in LFO/PMS system. [ABSTRACT FROM AUTHOR]

[Display omitted] • A more cost-effective and eco-friendly modification for enhancing oxygen activity. • Fragmented flaky structure endowed LaFeO 3 with more robust oxygen activity. • The gas yield and carbon conversion in the BCLG stage increased by 22.7% and 21.1%. • Residual char played a predominant role in the splitting stage. • Reaction mechanism of LaFeO 3 in BCLG coupled with CO 2 /H 2 O splitting was analyzed. Considering that the conventional modification of metal doping may bring excessive cost escalation and more pollution, for the sol–gel method, a more cost-effective and eco-friendly modification method was proposed to enhance the oxygen activity of LaFeO 3 and its doped oxygen carriers (OCs). In this work, LaFeO 3 OCs with fragmented flaky structure was prepared by modification of adjusting the sol to weak alkalinity with ammonia and adding the complexing agent ethylene glycol. Then, it was applied in Biomass chemical looping gasification (BCLG) coupled with CO 2 /H 2 O splitting to produce high-quality syngas and achieve cascade conversion of carbon in biomass, and its performance and reaction mechanism were investigated by fixed bed test. The results showed that the fragmented flaky structure endowed the LaFeO 3 OCs with more robust oxygen activity, thus realizing efficient lattice oxygen migration which increased the gas yield of BCLG stage from 695.6 mL/g to 851.2 mL/g at 900 °C, and the carbon conversion and gasification efficiency reached 65.6% and 64.4%, respectively. Despite the predominant role of residual char in the gas generation of splitting stage, the reduced OCs still possesses exceptional CO 2 and H 2 O splitting ability. Among them, CO 2 splitting was mainly carried out by the activation of Fe0 and alkaline active sites from the reduced OCs, while H 2 O splitting depended more on the decomposition of H 2 O molecules by oxygen vacancies. Moreover, this OCs exhibited outstanding stability in 10 cycles, and the total gas yield in two stages was consistently maintained around 1030.1 mL/g and 1069.6 mL/g, respectively. This work found that the LaFeO 3 OCs with fragmented flaky structure is a prospective material for chemical looping technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • LaFeO 3 can converts toluene to high-purity syngas in a fixed bed reactor. • LaFeO 3 prepared by TS performs the best among the five wet chemistry methods. • A new in-situ CLPO process for tar-containing syngas purification is proposed. • Tunable H 2 /CO ratio for syngas is achieved by adjusting toluene catalytic cracking. • A reverse flow design is proposed to achieve ∼100 % toluene conversion ratio. Tar is the by-product of coal and biomass gasification which decreases the purity of the primary syngas and causes blockages in the pipes. Chemical looping partial oxidation (CLPO) is a promising technology to convert tar to high-purity syngas in a sustainable way. Here, we synthesized LaFeO 3 perovskites as oxygen carriers with five different wet chemistry synthesis methods and tested their performance for toluene CLPO in a fixed-bed reactor. The template synthesis method presents the highest purity, the most oxygen species adjacent to oxygen vacancy, the best resistance to the carbon deposition, and exhibits the best performance in CLPO, with up to ∼100 % toluene conversion efficiency, up to ∼100 % CO selectivity, and the best recyclability. The H 2 /CO ratio in the syngas products varies between 0.86 and 2.2 in different stages of the toluene CLPO process. By adjusting the reaction time of toluene catalytic cracking, the H 2 /CO ratio is tunable within this range. Based on these results, we designed a new in-situ CLPO process for tar-containing syngas purification that can achieve tunable H 2 /CO ratio for syngas. In the process, toluene cracking occurs in front of toluene partial oxidation by using reverse flow design to simultaneously achieve ∼100 % toluene conversion ratio and high conversion rate. This work shows that LaFeO 3 is highly efficient in converting toluene to high-purity syngas, and it has the potential to convert tar-containing syngas in-situ to achieve energy- and cost-effective manufacture for high-value-added syngas products. [ABSTRACT FROM AUTHOR]

Highlights: [•] LaFeO3 and BiFeO3 prepared and tested as catalysts for heterogeneous Fenton reaction. [•] Nano-crystalline perovskites obtained by implementation of sol–gel method. [•] LaFeO3 and BiFeO3 showed high catalytic activity in phenol oxidation at pH 7. [•] Excellent stability of BiFeO3 in four re-use cycles. [•] Mechanistic studies based on isotope fractionation experiments indicate dominant role of OH. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis of YFeO3 and LaFeO3 perovskite catalysts via sucrose assisted solution-combustion. [•] Intensive fluctuation between the different oxidation states of Fe ions suggested with LaFeO3. [•] More effective activation of hydrocarbon and oxygen molecules on LaFeO3 than on YFeO3. [ABSTRACT FROM AUTHOR]

Abstract: The novel microspheres composed of perovskite LaFeO3 nanoparticles have been successfully prepared by hydrothermal method via self assembly process. Hydrothermal reaction conditions and citric acid concentration plays a vital role in the formation of LaFeO3 microspheres. The obtained microspheres have been structurally characterized by X-ray diffraction analysis (XRD) which confirms the single crystalline orthorhombic structure. The structural information was also confirmed from the Raman spectrum and the average crystallite size obtained from XRD increases with increasing hydrothermal reaction time. The composition and thermal decomposition processes of LaFeO3 were carefully investigated using energy dispersive spectroscopy (EDS) and thermogravimetric/differential thermal analysis (TG/DTA). Scanning electron microscopy (SEM) analysis indicates the formation of well-organized microspheres with an average diameter of 2–4μm and transmission electron microscopy (TEM) images reveal LaFeO3 nanoparticles with an average size of 85nm, which agrees well with the size obtained from XRD. A subsequent plausible formation mechanism of LaFeO3 microspheres has been explained in accordance with the Ostwald ripening process. The band gap energy was found to be 2.1eV using UV–Vis diffuse reflectance spectrum. Furthermore, the photodegradation of Rhodamine B (RhB) in aqueous solution under visible-light illumination was evaluated. [Copyright &y& Elsevier]

• The features of studied catalyst were tuned by introduction of A-site cation deficiency. • The strategy could help boost the generation of surface oxygen vacancy efficiently. • The mechanism related with surface properties was investigated in detail. • The surface features change was demonstrated based on experiment and theoretical calculation. Surface oxygen vacancies have been demonstrated to be an important factor for volatile organic compounds (VOCs) catalytic oxidation. In this work, the oxygen vacancy over LaFeO 3 perovskite oxides was tuned by the way of controlling A-site cation deficiency. The catalysts were synthesized through the Pechini method and investigated for the complete oxidation of toluene. Upon the strategy, the catalytic activity for the complete oxidation of toluene was enhanced obviously. The sample L 0.90 FO exhibited excellent catalytic performance, better than the stoichiometric sample LaFeO 3 and commercial Fe 2 O 3. Via analyzation of diversified characterization results, the introduction of A-site cation deficiency could affect the surface physicochemical properties to a certain extent, including enhanced oxygen vacancies, surface element valence state, and surface oxygen species content. Furthermore, through DFT calculation, the introduction of A-site cation deficiency could boost the formation of oxygen vacancies, consistent with the results of characterizations. Herein, the strategy of the introduction of A-site cation deficiency is one effective method to tune the surface oxygen vacancy which would benefit the catalytic performance of toluene catalytic oxidation. [ABSTRACT FROM AUTHOR]

• MOF gel was applied as precursor for preparation of perovskite-type oxides. • MOF gel derivatives retained chemical homogeneity of sol-gel and porous of MOF. • The prepared LaFeO 3 has high specific surface area and mesoporous structure. • LaFeO 3 shows good performance in all-solid-state symmetric supercapacitor. Sol-gel strategies have attracted enormous attention in synthesis of perovskite-type oxides due to their excellent chemical homogeneity and possibility in controlling the size, morphology, chemical properties and texture of particles. Nevertheless, their complicated, time-consuming process and weak control over porous structure impeded their potential use in preparation of energy storage materials. Herein, a simple and rapid strategy based on MOF gel (MIL-100-Fe) is developed for fabricating mesoporous perovskite-type materials. The MOF gel can be synthesized in controllable time duration without multi complexing agent, particular pH conditions and high temperature treatment. The synthesized perovskite LaFeO 3 has mesoporous structure and the pore size is concentrated at 2 nm, which contribute to a specific capacitance of 241.3 F g−1 at 1 A g−1 with retention of 68% even at a high current density of 20 A g−1. Meanwhile, the all-solid-state symmetric supercapacitor shows a wide potential window of 1.8 V, and an outstanding energy density of 34 W h kg−1 at a power density of 900 W kg−1 with 92.2% capacitance retention after 5000 cycles, outperforming previously reported perovskite-type electrode materials and even comparable to MOF derived iron oxides. Thus, this study opens a new way to construct porous perovskite-type electrode materials for supercapacitors, which can combine the chemical homogeneity of sol-gel technology and the porous properties of MOF template together. [ABSTRACT FROM AUTHOR]