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Porous carbon encapsulated non-precious metal nanocatalysts have recently opened the ways towards the development of high-performance water remediation and energy conversion technologies. Herein, we report a facile, scalable and green synthetic methodology to fabricate porous carbon encapsulated transition metal nanocatalysts (M@TP: M = Cu, Ni, Fe and Co) using commercial tissue paper. The morphology, crystalline structure, chemical composition and textural properties of the M@TP nanocatalysts were thoroughly characterized. The catalytic activity of the M@TP nanocatalysts was investigated for the degradation of Congo red (CR) via peroxymonosulfate activation. Co@TP-6 was found to be the most active catalyst allowing 97.68% degradation in 30 min with a higher rate constant of 0.109 min−1. The nanocatalysts also displayed a carbon shell thickness-dependent electrocatalytic hydrogen evolution reaction (HER) activity, most likely due to the shielding effect of the carbon layers over the electron transfer (ET) processes at the metal core/carbon interfaces. Remarkably, the Ni@TP-6 electrocatalyst, with the smaller carbon shell thickness, showed the best electrocatalytic performance. They delivered an ultralow onset potential of −30 mV vs RHE, an overpotential of 105 mV at a current density of 10 mA·cm−2 and an excellent electrochemical stability to keep the 92% of the initial current applied after 25000 s, which is comparable with the HER activity of the state-of-the-art Ni-based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of 2D Co x Ni y -MOF were synthesized by ultrasonic method. • Ti 3 C 2 T x nanosheets converting the OER process to a reaction-limited one. • 2D Co2NiMOF/MXene were prepared by electrostatically directed assembly. • The MOF/MXene interface allows for the rapid electron and ion transfer. • Benefiting from thin 2D/2D heterostructure, exhibit enhanced OER performance. Hydrogen production from water electrolysis is severely restricted by the poor reaction kinetics of oxygen evolution reaction (OER). In this work, a series of two-dimensional (2D) composites MOF/Ti 3 C 2 T x (the MXene phase) were fabricated by electrostatically directed assembly and used as catalysts for OER. The obtained composite materials exhibit enhanced electrocatalytic properties, thanks to the ultrathin 2D/2D heterostructure with abundant active sites in Co2Ni-MOF and the high electronic conductivity of Ti 3 C 2 T x. Among all the catalysts, Co2Ni-MOF@MX-1 achieved the best oxygen evolution performance with the lowest Tafel slope (51.7 mV dec−1) and the lowest overpotential (265 mV on carbon paper) at the current density of 10 mA cm−2. These results demonstrated that the synthesis of 2D composite materials by electrostatically directed assembly could be a feasible and promising method for the preparation of 2D heterostructure catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • In 2 O 3 quantum dots were successfully loaded on g-C 3 N 4 by pre-forming In–N bonds. • High-temperature oxidation can improve the oxygen adsorption capacity of g-C 3 N 4. • S-scheme transfer exhibits excellent photoelectric conversion efficiency. • Hydroperoxide C β intermediate was an important intermediate in lignin β–O–4 bond cleavage reaction. The graphitic carbon nitride (g-C 3 N 4) photocatalysis has emerged as a clean method for cleaving lignin-linked bonds due to its mild and sunlight-driven reaction conditions. The fast electron–hole pair complex of g-C 3 N 4 constrains its degradation efficiency, making the heterojunction construction a popular solution. The conventional methods of preparing g-C 3 N 4 heterojunctions by physical mixing destroy π-conjugations in g-C 3 N 4 , reducing the adsorption of lignin containing benzene rings. In this study, a novel indium oxide (In 2 O 3) quantum dot–g-C 3 N 4 0D/2D heterojunction was prepared through the high-temperature oxidation of pre-prepared indium-doped g-C 3 N 4. The introduction of In 2 O 3 at the quantum dot level minimizes the interference with lignin adsorption capacity. The strong combination of the two (In 2 O 3 and g-C 3 N 4) increases the intersection interface area, promoting the S-scheme transfer route of the photogenerated electrons. Consequently, this enhances the photoelectric conversion efficiency and carrier lifetime of the heterojunction, and inhibits the rapid recombination of photogenerated electron–hole pairs in g-C 3 N 4. The proposed heterojunction was 3 times more efficient than g-C 3 N 4 alone for selective cleavage of lignin β–O–4 bonds after 2 h of sunlight irradiation. Combined with inhibitor experiments and gas chromatography–mass spectrometry analysis, this paper defines the reactive oxides and proposes a cleavage pathway for the lignin β–O–4 bonds in In 2 O 3 –g-C 3 N 4 heterojunction system. [ABSTRACT FROM AUTHOR]

Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres for enhanced oxygen evolution reaction. [Display omitted] • Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres. • FeNi/Mo 2 C/NC supports strongly accelerated electron transfer, thereby improving the OER kinetics. • FeNi/Mo 2 C/NC hybrids will hold promise in development of electrode materials. The rapid depletion of fossil fuels results in significant environmental pollution. Consequently, researching environmentally friendly and cost-effective electrocatalysts with exceptional oxygen evolution reaction (OER) capabilities holds immense importance in enhancing the efficient utilization of resources. In this paper, a straightforward and cost-effective method was employed to produce Fe-Ni alloy-supported N -doped carbon hollow nanospheres (FeNi/Mo 2 C/NC) using self-assembled molybdenum dopamine spheres (Mo-PDA-HS) as a substrate. The inclusion of iron and nickel addressed the issue of aggregation and collapse in Mo-PDA-HS nanostructures at high temperatures, while adjusting the electronic structure of the composites to achieve efficient OER activity. The composite displayed a low overpotential (η10 mA = 304 mV) and a minimal Tafel slope (41.8 mV/dec-1). This study introduces a simple strategy for constructing structurally robust and non-aggregating Mo 2 C nanostructures, along with a direct method for designing cost-effective and high-performance catalysts for OER. [ABSTRACT FROM AUTHOR]

[Display omitted] • The internal channels of the crystal structure are extended by the introduction of larger radius Ce3+, which increases the transport rate of Na+. • The introduction of Mo6+ replacing the V site leads to a beneficial n -type doping effect and facilitates the transportation of electrons. • CeO 2 functions as an n -type semiconductor and a conductive additive to significantly enhance the electrical conductivity. • CeO 2 acts as an oxygen buffer, aiding in the preservation of active metal dispersion during operation and facilitating efficient electron transfer between CeO 2 and [VO 6 ]. • CeMo0.07@8wt.%CeO 2 sample has excellent sodium storage performance at both half and asymmetric full cells. Na 3 V 2 (PO 4) 3 (NVP) is highly valued based on the stable construction among the polyanionic compounds. Nevertheless, the drawback of low intrinsic conductivity has been impeded its further application. In this paper, the internal channels of the crystal structure are extended by the introduction of larger radius Ce3+, which increases the transport rate of Na+. The introduction of Mo6+ replacing the V site leads to a beneficial n -type doping effect and facilitates the transportation of electrons. Besides, CeO 2 cladding is introduced to further enhance the electronic conductivity of NVP system. Initially, CeO 2 serves as an n -type semiconductor and functions as a conductive additive to significantly enhance the electronic conductivity of the electrode, thereby improving the electrochemical characteristics. Moreover, CeO 2 functions as an oxygen buffer, aiding in the maintenance of active metal dispersion during operation and enabling efficient electron transfer between CeO 2 and [VO 6 ] octahedra in NVP, thus fostering outstanding electrical connectivity between the oxides. CeO 2 cladding can be effectively integrated with the carbon layer to stabilize the NVP system. Comprehensively, the modified Na 3 V 1.79 Ce 0.07 Mo 0.07 (PO 4) 3 /C@8wt.%CeO 2 (CeMo0.07@8wt.%CeO 2) composite exhibits excellent rate and cycling properties. It delivers a capacity of 113.4 mAh/g at 1C with a capacity retention rate of 80.3 % after 150 cycles. Even at 10C and 40C, it also submits high capacities of 84.7 mAh/g and 76 mAh/g, respectively. Furthermore, the CHC//CeMo0.07@8wt.%CeO 2 asymmetric full cell possesses excellent sodium storage property, indicating its prospective application potentials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new MgFe 2 O 4 /Bi 2 WO 6 composite photocatalyst was successfully prepared by wet ball milling process. • Through DFT calculations and a series of characterizations, it was confirmed that the MgFe 2 O 4 /Bi 2 WO 6 composite material conforms to the Z-scheme electron transfer mechanism. • The degradation rate of TCH by 25%-MgFe 2 O 4 /Bi 2 WO 6 composite photocatalytic material is as high as 95.82%. • · OH and · O 2 – are the main active substances in this photocatalytic reaction. • The composite has high stability in repeated experiments. In this study, a new Z-scheme MgFe 2 O 4 /Bi 2 WO 6 heterojunction was successfully prepared by hydrothermal and wet ball milling process. The results of the study showed that after 90 min of visible light exposure, the photocatalytic degradation of tetracycline hydrochloride (TCH) by 25%-MgFe 2 O 4 /Bi 2 WO 6 heterojunction was as high as 95.82%, and the highest photocatalytic rate (0.0281 min−1) was 4.61 and 3.43 times higher than that of pure Bi 2 WO 6 (0.0061 min−1) and MgFe 2 O 4 (0.0082 min−1), respectively. Furthermore, spin-polarized density functional theory (DFT) calculations were performed to provide additional evidence of the presence of a Z-scheme charge transfer mechanism between MgFe 2 O 4 and Bi 2 WO 6. We investigated the effects of initial TCH concentration, pH, coexisting ions and different water sources on the efficiency of photocatalytic degradation of TCH in composite samples. The recovery experiments demonstrated that the MgFe 2 O 4 /Bi 2 WO 6 composites had good stability and repeatability. A series of experimental results showed that 25%-MgFe 2 O 4 /Bi 2 WO 6 had a larger specific surface area, better ultraviolet and visible absorbance, superior charge transfer and higher efficiency of photogenerated electron-hole pair separation. This paper provides new ideas for the design and preparation of new Z-scheme heterojunctions and has great prospects for practical applications in the field of wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A one-pot strategy was developed for the successful formation of PdPtNi porous nanosheets. • The PdPtNi PNS provide ideal electrocatalytic active sites. • The PdPtNi PNS displayed improved electrocatalytic performance toward MOR and EOR. Bimetallic two-dimensional (2D) nanomaterials are widely used in electrocatalysis owing to their unique physicochemical properties, while trimetallic 2D materials of porous structures with large surface area are rarely reported. In this paper, a one-pot hydrothermal synthesis of ternary ultra-thin PdPtNi nanosheets is developed. By adjusting the volume ratio of the mixed solvents, PdPtNi with porous nanosheets (PNSs) and ultrathin nanosheets (UNSs) was prepared. The growth mechanism of PNSs was investigated through a series of control experiments. Notably, thanks to the high atom utilization efficiency and fast electron transfer, the PdPtNi PNSs have remarkable activity of methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). The mass activities of the well-tuned PdPtNi PNSs for MOR and EOR were 6.21 A mg−1 and 5.12 A mg−1, respectively, much higher than those of commercial Pt/C and Pd/C. In addition, after durability test, the PdPtNi PNSs exhibited desirable stability with the highest retained current density. Therefore, this work provides a significant guidance for designing and synthesizing a new 2D material with excellent catalytic performance toward direct fuel cells applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Solar energy conversion into hydrogen (H 2) energy has attracted much attention. However, the low light utilization rate and fast carrier recombination of photocatalysts extremely limit the practical application of photocatalytic H 2 production. In this paper, MoSe 2 -NiSe with abundant active sites and interfacial electronic structures as dual co-catalysts were assembled on g-C 3 N 4 nanosheets (NSs) vis a solvothermal reaction process. MoSe 2 -NiSe/g-C 3 N 4 NSs composite exhibited improved light absorption and photoelectrochemical properties. The photocatalytic H 2 production rate of MoSe 2 -NiSe/g-C 3 N 4 composite achieved 2379.04 μmol·h−1·g−1, which is 99.25, 1.44, and 3.67 times those of pure g-C 3 N 4 nanosheets (23.97 μmol·h−1·g−1), MoSe 2 /C 3 N 4 (1654.57 μmol·h−1·g−1), and NiSe/C 3 N 4 (649.08 μmol·h−1·g−1), respectively. The apparent quantum efficiency (AQE) value of MoSe 2 -NiSe/g-C 3 N 4 achieved 4.07 % under light at λ = 370 nm. The corresponding characterization and experiments proved that 2D ultrathin g-C 3 N 4 NSs with a large surface area and short charge-transfer distance could facilitate light scattering and the transport of photoexcited electrons. MoSe 2 -NiSe, as a dual co-catalyst, showed strong electronic synergistic interaction between the interfaces, thus improving the conductivity and promoting the electron transfer process. [ABSTRACT FROM AUTHOR]

[Display omitted] The self-standing graphene membranes are considered as ideal electrode materials for supercapacitors. However, maintaining highly regularized and uniform graphene membranes with satisfied electrochemical performance is still a challenge. Herein, with the chelation of metal cation and the radial shear force introduced by high-speed spinning, the uniform interlayer channels and shrunken cracks between adjacent nanosheets can be achieved in the metal-intercalated graphene oxide (GO) membranes, thus realizing regularization both in normal and radial direction. With the promotion in electron transfer and electrolyte penetration, the iron cross-linked GO membrane with spin coating for 40 cycles exhibits a high specific capacitance (427 F g−1 at 1 A g−1) and rate capability (42.6% capacitance retention from 1 to 40 A g−1), as well as excellent cyclic capability (90.5% capacitance retention after 20,000 cycles). Particularly, a 21% increasement in capacitance can be achieved after high-speed spinning treatment. Moreover, the spin regularization strategy can be extended to GO membranes cross-linked by various multi-valence metal cations, the electrochemical performance of metal-cation cross-linked GO membrane electrodes after high-speed spinning treatment can also be improved obviously. Therefore, this paper provides a novel method to fabricate highly ordered GO membranes with promising electrochemical performance, which presents an immense potential application in membrane materials applied in energy storage, separation and catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface nitrogen vacancy is instrumental in the chemisorption and activation of H 2 O. • Surface nitrogen vacancy and extended photocarrier lifetime has improved H 2 production. • S-scheme band of AgI/g-C 3 N 4 is conjectured by the experiments and DFT calculations. AgI/g-C 3 N 4 S-scheme heterojunction with a unique electron transfer pathway was developed as a catalyst for H 2 evolution. We discussed the behavior of chemisorption and photoexcited charge carriers in photocatalytic reduction on the S-scheme AgI/g-C 3 N 4 heterojunction. It was demonstrated that the path of charge transfer mediated by S-scheme AgI/g-C 3 N 4 heterojunction was favorable for the improvement of electron utilization in photocatalysis. The advantage of S-scheme heterojunction was that the holes in the valence band (VB) of g-C 3 N 4 could recombine with the electrons in the conduction band (CB) of AgI due to the built-in electric field. Electrons on the CB of g-C 3 N 4 and holes on the VB of AgI were preserved for further photocatalytic reaction. Therefore, a distinctive electron transfer pathway was introduced in the S-scheme heterojunction. In addition, the lifetime of charge carriers was prolonged, and the reduced ability of electrons was increased as compared to reference g-C 3 N 4. It not only decreased the energy required for electron excitation, but also reduced the energy consumption for the charge transfer. This paper provided a new strategy to improve the utilization of photogenerated electrons and chemisorption of water for photocatalytic H 2 O splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient, stable and low-cost catalysts are essential for improving the efficiency of hydrogen evolution reactions. Herein, the MoO 2 @Ni 2 P heterostructure electrocatalyst was synthesized in a self-supported system on a carbon paper (CP) by two-step deposition and phosphorization at low temperature. The self-supported nanoarray structure makes the catalyst to effectively and efficiently transfer electrons and exposes more of its active sites. Moreover, the strong interaction between Ni 2 P and MoO 2 helps to effectively optimize the electronic structure. The density of states calculations demonstrate that there is an increase in the density of electronic states near the MoO 2 /Ni 2 P Fermi level. This shows that MoO 2 /Ni 2 P has fast charge transfer kinetics. MoO 2 modulates the d-band center of nickel, resulting in moderate adsorption/desorption of hydrogen. The above results show that MoO 2 @Ni 2 P has good hydrogen evolution activity. The experimental results show that the overpotential (η 10) of MoO 2 @Ni 2 P/CP in the alkaline environment is only 57 mV with a Tafel slope of 61 mV dec−1. It is similar to the commercial noble-metal catalysts and outperforms most reported catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient, stable and low-cost catalysts are essential for improving the efficiency of hydrogen evolution reactions. Herein, the MoO 2 @Ni 2 P heterostructure electrocatalyst was synthesized in a self-supported system on a carbon paper (CP) by two-step deposition and phosphorization at low temperature. The self-supported nanoarray structure makes the catalyst to effectively and efficiently transfer electrons and exposes more of its active sites. Moreover, the strong interaction between Ni 2 P and MoO 2 helps to effectively optimize the electronic structure. The density of states calculations demonstrate that there is an increase in the density of electronic states near the MoO 2 /Ni 2 P Fermi level. This shows that MoO 2 /Ni 2 P has fast charge transfer kinetics. MoO 2 modulates the d-band center of nickel, resulting in moderate adsorption/desorption of hydrogen. The above results show that MoO 2 @Ni 2 P has good hydrogen evolution activity. The experimental results show that the overpotential (η 10) of MoO 2 @Ni 2 P/CP in the alkaline environment is only 57 mV with a Tafel slope of 61 mV dec−1. It is similar to the commercial noble-metal catalysts and outperforms most reported catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystalline Ni(OH) 2 /Amorphous NiMoS electrocatalyst were designed and synthesized by two-step hydrothermal process. • The as-obtained material shows excellent hydrogen evolution over all pH ranges. • The synergistic mechanism and the role of crystalline Ni(OH) 2 and amorphous NiMoS was elucidated. Designing and fabricating efficient electrocatalysts is a practical step toward the commercial application of the efficient hydrogen evolution reaction (HER) over all pH ranges. Herein, novel Ti@Ni(OH) 2 -NiMoS heterostructure with interface between crystalline Ni(OH) 2 and amorphous NiMoS was rationally designed and fabricated on Ti mesh (denoted as Ti@Ni(OH) 2 -NiMoS). Acid etching and calcination experiments helped in accurate elucidation of the synergistic mechanism as well as the vital role on crystalline Ni(OH) 2 and amorphous NiMoS. In acidic solutions, the HER performance of Ti@Ni(OH) 2 -NiMoS was mainly attributed to the amorphous NiMoS. In neutral, alkaline, and natural seawater solutions, the HER performance was mainly determined by the synergistic interface behaviors between the Ni(OH) 2 and NiMoS. The crystalline Ni(OH) 2 accelerated water dissociation kinetics, while the amorphous NiMoS provided abundant active sites and allowed for fast electron transfer rates. To deliver current densities of 10 mA·cm−2 in acidic, neutral, alkaline, and natural seawater solutions, the Ti@Ni(OH) 2 -NiMoS required overpotentials of 138, 198, 180 and 371 mV, respectively. This paper provides general guidelines for designing efficient electrocatalyst with crystalline/amorphous interfaces for efficient hydrogen evolution over all-pH ranges. [ABSTRACT FROM AUTHOR]

Carbon-metal composites are promising multifunctional electrocatalysts, but it is still challenging to prepare carbon-metal composites with tunable structure and strong metal-carbon interactions. Here, we present a unique gas-foaming assembly strategy to prepare cytosine-Co chelate derived Co and N codoped carbon nanotube (Co-NCNT). The structure for Co-NCNTs could be easily controlled by regulating cytosine-Co coordination or the carbonization temperature. The optimal Co-NCNT possesses homogeneous distributed NCNTs (10 nm), CoO x (5 nm) and CoN x moieties to synergistically boost electrochemical processes, and offer mesoporous nanosheet architecture to guarantee fast mass migrate and electron transfer. As a result, Co-NCNT shows remarkable ORR performance (onset potential of 0.93 V in 0.1 M KOH electrolyte) along with significant OER and HER activity. More important, it was found that CoN x moieties are responsible for the remarkable electrocatalytic activity in Co-NCNTs, because CoN x could alter active center, enhance metal-carbon synergy, decrease interfacial resistance and reinforce the strength of composites. Therefore, this paper not just demonstrates an advanced multi-functional electrocatalyst, but could also give deep understanding on the designing of multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

• TBAOH assisted synthesis of ultrathin BiOCl-T nanosheets with exposed (1 1 0) face. • Deionized water was used as the solvent for the preparation of BiOCl-T. • BiOCl-T exhibited enhanced charge separation efficiency. • BiOCl-T displayed superior photocatalytic activity in CBZ degradation. • h+, O 2 −, and OH predominated the photocatalytic degradation process of CBZ. Ultrathin nanosheets show great promise in photocatalytic technology, due to short path for electron transfer and large surface for reactant adsorption. However, there is no report that ultrathin nanosheets photocatalyst has been used to degrade carbamazepine (CBZ) in aquatic environment. This paper aimed at fabricating ultrathin BiOCl nanosheets to improve the photocatalytic degradation efficiency of CBZ. Herein, tetrabutylammonium hydroxide (TBAOH) was firstly applied to synthesize ultrathin BiOCl nanosheets (BiOCl-T) by a simple hydrolysis route in water at ambient conditions. TBAOH could act as a structure-directing agent, determining the structure and property of BiOCl-T. Assisted by TBAOH, BiOCl-T exhibited ultrathin nanosheets structure with preferential exposed (1 1 0) face. PL, photocurrent density, and EIS Nyquist plots demonstrated the enhanced charge separation efficiency in BiOCl-T. Furthermore, BiOCl-T displayed large pore size and specific surface area. Thus, BiOCl-T showed high photocatalytic activity toward CBZ degradation under simulated sunlight. Upon 30 min irradiation, the degradation efficiency of CBZ was 91.1% with fast degradation kinetics, which is 2.46 times higher than ordinary BiOCl. Active species of h +, O 2 −, and OH contributed to CBZ degradation reaction. The obtained result provides a novel viewpoint to fabricate ultrathin nanosheets and broadening their application in the degradation of recalcitrant pharmaceuticals. [ABSTRACT FROM AUTHOR]

The energy level diagram for electronic transfer vs. Vacuum level; (B and C) The photocatalytic mechanism over EY-sensitized UiO-66/WP. The abundant transition metal phosphides co-catalysts on the earth can satisfy the sustainable and clean solar H 2 production through photocatalytic water splitting, which is promising to replace the rare precious metals, such as Pt, Au, Pd, Ru and so on. In this paper, we use the temperature-programmed solid phase method to prepare WP nanoparticles. Based on the Density Functional Theory (DFT) calculations, we demonstrate that the WP nanoparticles possess outstanding electrical conductivity and excellent capability to transport electrons. WP nanoparticles are loaded onto the surface of UiO-66 via the ultrasound-assisted impregnation method to induce a highly efficient visible-light photocatalytic H 2 production activity of 384 µmol in 5 h, which is 10.67 times than that of pure UiO-66. The catalytic performance is attributed to the excellent metallic conductivity and the favourable Fermi level position of WP nanoparticles. Further studies of PL, TRPL and Mott-Schottky curves, we can not only know that the modification of WP nanoparticles do improve the electron transfer ability, but also that the matched work functions between the EY and UiO-66 provides a feasible thermodynamic path for the transmission of electrons. Our work demonstrates that the earth-abundant transition metal phosphides material have the potential to construct cheaper and high catalytic performance photocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogen evolution reaction (HER) from water splitting is a promising way to promote the utilization of renewable energy. Designing and fabricating electrocatalysts with low cost, high catalytic activity and robust stability is desirable. In response, we prepared carbon shells encapsulating ultrafine β-Mo 2 C nanoparticles with N and P dual-doping as advanced electrocatalyst used for HER in both acidic and alkaline mediums. This paper gives a discussion on element doping and porosity which have influence on the HER performance. As introducing heteroatoms into carbon matrix to create active sites and enhance electron transfer capacity, the as-prepared electrocatalyst exhibits high catalytic activity with low overpotential of 117 mV and 121 mV to achieve current density of 10 mA cm−2 in acidic and alkaline solutions. Due to the strategy of carbon shells encapsulating, the catalyst presents robust stability for a long time at various applied potential. Furthermore, the design idea of using multiple strategies preparing catalysts may serve some inspiration to fabricate advanced electrocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the facile and general synthesis of alkaline-earth metal manganites, denoted as A(Mg, Ca, Ba)Mn x O y , for efficient degradation of high-concentration phenolic compounds via catalytic ozonation. The representative CaMn x O y oxides show a hierarchical spherical structure constructed by crystalline nanorods and numerous macropores. They possess mixed Mn4+/Mn3+ chemical valences and abundant surface hydroxyl (OH) groups. The ozone (O 3) decomposition rate on the CaMn x O y catalysts is greatly accelerated and follows the first-order law. These catalysts are promising for the degradation of phenolic compounds via catalytic ozonation, exhibiting rapid pseudofirst-order degradation kinetics, a high total organic carbon (TOC) removal efficiency and an excellent stability. Under optimized conditions (a low O 3 dosage of 1.5 mg/min and a catalyst dosage of 7.5 g/L), for the treatment of concentrated phenol (50–240 mg/L), the CaMn x O y catalysts show 100% degradation and 50–70% mineralization within 1.0 h. The Ca2+ ions are essential to create redox Mn4+/Mn3+ couples and to significantly reduce manganese leaching. High surface ratios of Mn4+/Mn3+ and OH/lattice oxygen (O lat) are beneficial for enhancing the catalytic performance. Superoxide anion free radicals (O 2 –) and singlet oxygen (1O 2) are the predominant reactive species for the oxidation degradation. The O 2 – reaction pathway is proposed. Specifically, the surface OH sites activate O 3 , displaying highly enhanced decomposition rates. The generated O 2 – and 1O 2 play a role in oxidation. The redox Mn4+/Mn3+ and the O lat /oxygen vacancy (O lat /O vac) couples play important roles in electron transfer. The proposed mechanism is supported by active site probing, radical scavenging, spectroscopic studies, and the results in the degradation of substituted phenols. [ABSTRACT FROM AUTHOR]