High Electrocatalytic Activity Research Articles

The formation of unsaturated IrOx in SrIrO3 by cobalt-doping for acidic oxygen evolution reaction

Electrocatalytic water splitting is a promising route for sustainable hydrogen production. However, the high overpotential of the anodic oxygen evolution reaction poses significant challenge. SrIrO3-based perovskite-type catalysts have shown great potential for acidic oxygen evolution reaction, but the origins of their high activity are still unclear. Herein, we develop a Co-doped SrIrO3 system to enhance oxygen evolution reaction activity and elucidate the origin of catalytic activity. In situ experiments reveal Co activates surface lattice oxygen, rapidly exposing IrOx active sites, while bulk Co doping optimizes the adsorbate binding energy of IrOx. The Co-doped SrIrO3 demonstrates high oxygen evolution reaction electrocatalytic activity, markedly surpassing the commercial IrO2 catalysts in both conventional electrolyzer and proton exchange membrane water electrolyzer.

Moderately Reconstructed Ternary Metal Nitride Nanoparticles for Highly Efficient and Robust Freshwater and Seawater Oxidation under Industrial Current Density

Transition metal nitrides (TMNs) electrocatalysts experience rapid performance degradation during oxygen evolution reaction (OER) due to severe and irreversible electrochemical reconstruction, impeding their practical application in electrochemical water splitting. To address this issue, ternary metal (Ni, Fe, Cr) nitride nanoparticles on spongy nitrogen‐doped disordered carbon skeleton electrocatalyst (NFCN/C) is synthesized using a novel one‐pot pyrolysis of eutectic mixture method. The ionomer‐free NFCN/C electrode, which undergoes moderate electrochemical reconstruction, demonstrates high OER performance in both alkaline freshwater and seawater solutions, achieving a current density of 250 mA cm−2 with low overpotentials of 349 and 364 mV, respectively. The NFCN/C anode with Pt/C cathode delivers 10 mA cm−2 at a low cell voltage of 1.49 V and exhibits long‐term durability of 450 h at 500 mA cm−2. In situ Raman spectroscopy and ultraviolet photoelectron spectroscopy (UPS), along with pre‐ and post‐characterizations, elucidate that both high electrocatalytic activity and robustness of NFCN/C for OER stem from the proposed intrinsic strategy integrating physical and electronic structures. This work paves the way for designing highly efficient and robust TMNs electrocatalysts with moderate electrochemical reconstruction for industrial freshwater and seawater electrolysis.

Ru nanoparticles decorating ferrocene-based metal-organic framework for efficient and stable water-splitting electrocatalyst

The development of stable and efficient electrocatalysts based on metal-organic frameworks represents a main challenge for the overall water splitting process. Here, the ferrocene-based nickel metal-organic framework (NiFc-MOF) on nickel foam (NF) was synthesized using nickel chloride and 1, 1′-ferrocenedicarboxylic acid (FcDA) via a simple solvothermal method, and Ru nanoparticles (NPs) were reduced by FcDA and in situ grown on the surface of NiFc-MOF nanosheets. The as-prepared cactus-like Ru0.3@NiFc-MOF exhibits high electrocatalytic activity for hydrogen evolution reaction (HER) with a low overpotential of 25 mV@10 mA cm−2 and a Tafel slope of 45.05 mV dec−1. To reach a current density of 10 mA cm−2 for the oxygen evolution reaction (OER), a low overpotential of 210 mV was required. The assembled water electrolysis cell using Ru0.3@NiFc-MOF as bifunctional electrocatalysts only requires a voltage of 1.47 V to achieve a current density of 10 mA cm−2, indicating excellent electrolytic water splitting performance. In addition, the electrocatalytic activity of Ru0.3@NiFc-MOF's can keep the stability for 120 h Ru0.3@NiFc-MOF exhibits exceptional electrocatalytic performance, which can be attributed to both the intrinsic activity of Ru sites and the multiple active sites of NiFc-MOF.

Cr dopant regulating d-orbital electronic configuration of NiFe spinel oxide to improve oxygen evolution reaction in Zn-air battery

Significant advancements towards enhancing the catalytic activity of spinel ferrites in oxygen evolution reaction (OER) have been achieved, however, further studies are required on this regard. In this study, Cr-doped spinel ferrite (NiFe2O4) embedded in N-doped C (Cr-NiFe2O4@NC) was synthesized via a high-temperature treatment using an NiFe Prussian blue analog as a precursor and K2Cr2O7 as a Cr source. Owing to the strong octahedral site preference energy, Cr3+ ions were successfully doped into octahedral sites and tailored the electronic configuration of NiFe2O4, as confirmed by XPS. The Cr-substituted Cr-NiFe2O4@NC exhibited the overpotential of 241 mV at 10 mA cm−2, which was smaller than that of NiFe2O4@NC (266 mV) at the same current density. Meanwhile, the Tafel slope of Cr-NiFe2O4@NC (65.32 mV dec−1) was also lower than that of NiFe2O4@NC (86.96 mV dec−1). Therefore, the Cr substitution can improve the electrocatalytic OER performance of NiFe2O4@NC. In particular, an assembled rechargeable Zn-air battery using Cr-NiFe2O4@NC as the cathode catalyst afforded a high power density (61.1 mA cm−2) together with a high specific capacity (740 mA g−1). Amazingly, it could power light-emitting diodes, demonstrating its real-world application. Density functional theory calculations revealed that Cr ion doping led to electron transfer in NiFe2O4, resulting in a density of electronic states close to the Fermi level, which probably regulated the adsorption/desorption behaviors of oxygenate intermediates (*O and *OOH), thus promoting the reaction kinetics of the OER. This study provides a helpful basis for the development of spinel oxides with high electrocatalytic OER activity and durability via cation doping.

Synergistic activation of lamellar bismuth selenide anchored functionalized carbon nanofiber for detecting hazardous carbendazim in environmental water samples

Pesticides pollute natural water reservoirs through persistent accumulation. Therefore, their toxicity and degradability are serious issues. Carbendazim (CBZ) is a pesticide used against fungal infections in agricultural crops, and its overexploitation detrimentally affects aquatic ecosystems and organisms. It is necessary to design a logical, efficient, and field-deployable method for monitoring the amount of CBZ in environmental samples. Herein, a nano-engineered bismuth selenide (Bi2Se3)/functionalized carbon nanofiber (f-CNF) nanocomposite was utilized as an electrocatalyst to fabricate an electrochemical sensing platform for CBZ. Bi2Se3/f-CNF exhibited a substantial electroactive surface area, high electrocatalytic activity, and high conductivity owing to the synergistic interaction of Bi2Se3 with f-CNF. The structural chemical compositions and morphology of the Bi2Se3/f-CNF nanocomposite were confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM). Electrochemical analysis was carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The voltammetry and impedance experiments exposed that the Bi2Se3/f–CNF–modified GCE has attained adequate electrocatalytic function with amended features of electron transportation (Rct = 35.93 Ω) and improved reaction sites (0.082 cm2) accessible by CBZ moiety along with exemplary electrochemical stability (98.92%). The Bi2Se3/f-CNF nanocomposite exhibited higher sensitivity of 0.2974 μA μM−1cm−2 and a remarkably low limit of detection (LOD) of 1.04 nM at a broad linera range 0.001–100 μM. The practicability of the nanocomposite was tested in environmental (tap and pond water) samples, which supports excellent signal amplification with satisfactory recoveries. Hence, the Bi2Se3/f-CNF nanocomposite is a promising electrode modifier for detecting CBZ.

Preparation of Polycurcumin-Modified Graphite Electrode via Electropolymerization and its Application for Determining Cd<sup>2+</sup>

The graphite electrode was changed by applying cyclic voltammetry to electropolymerized curcumin. Then, the polycurcumin-modified graphite electrodes (GECU) were used to determine Cd2+ concentration. The results showed that the GECU electrodes had higher electrocatalytic activity toward Cd2+ than bare graphite electrodes. Furthermore, the effect of the scan rates showed that the electrochemical process controlling the redox behavior of Cd2+ on GECU is a diffusion-controlled electrochemical process. At Cd2+ ranging from 0.22 to 11.03 ppm, the relationship between oxidation peak current (Ip) and Cd2+ concentration follows the linear regression equation of Ip = 73.024[Cd2+] + 722.02 (μA, R2 = 0.9936). It means that under experimental conditions, an increase in Cd2+ from 0.22 to 11.03 ppm can increase the Ip value. On the other hand, At Cd2+ ranging from 11.03 to 55.07 ppm, the relationship between Ip and Cd2+ concentration follows the linear equation of Ip = 24.227[Cd2+] + 1212.6 (μA, R2 = 0.9920). The LOD and LOQ were determined at low Cd2+ concentrations, namely 0.86 ppm, and 2.84 ppm, respectively. Furthermore, the suggested modification has been used successfully and with satisfactory recoveries to determine the presence of Cd2+ in laboratory liquid wastewater.

Ball milling-engineered nanostructured MoSe2/graphite electrocatalyst: Achieving superior hydrogen evolution with a high density of active sites

Nanostructured MoSe2 and its composites with graphite nanoparticles were prepared by a simple, inexpensive, and productive ball-milling method, demonstrating their superior effectiveness as electrocatalysts for the hydrogen evolution reaction (HER). The study revealed that the ball-milling duration significantly influences the prepared nanomaterials' morphology and electrocatalytic properties. The materials prepared in this way are characterized by significant delamination of both components and high defectiveness of molybdenum diselenide. The introduction of graphite nanoparticles into the molybdenum diselenide composition significantly enhances the material's electrocatalytic properties. It has been established that the electrocatalyst based on gMoSe2/Gr(2h) is characterized by a Tafel slope of 40 mV/dec and a potential of −75 mV at a current density of 10 mA/cm2. The electrode modified with gMoSe2/Gr(2h) demonstrates exceptional stability for over 20 hours while maintaining a high current density of approximately 450 mA/cm2 at −300 mV. The study establishes that the high electrocatalytic activity of materials obtained in this manner is directly related to the presence of a high concentration of selenium vacancies in their structure, which can act as catalytically active centers in HER.

Molten salt electrosynthesis of self-supporting FeCoNi medium entropy alloy electrocatalysts for efficient oxygen evolution reactions

High/medium entropy alloys (HEAs/MEAs) with high electrocatalytic activity have attracted great attention in water electrolysis applications. However, facile synthesis of self-supporting high/medium entropy alloys electrocatalysts with rich active sites through classical metallurgical methods is still a challenge. Here, a self-supporting porous FeCoNi MEA electrocatalyst with nanosheets-shaped surface for oxygen evolution reaction (OER) was prepared by a one-step electrochemical process from the metal oxides in molten CaCl2. The formation of the FeCoNi MEA is attributed to the oxides electro-reduction, high-temperature diffusion and solid solution. Additionally, the morphology and structure of the FeCoNi MEA can be precisely controlled by adjusting the electrolysis time and temperature. The electronic structure regulation and the reduced energy barrier of OER from the “cocktail effect”, the abundant exposed active sites brought by surface ultrathin nanosheets, the good electronic conductivity and electrochemical stability from the self-supporting structure enable the FeCoNi MEA electrode shows high-performance OER electrocatalysis, exhibiting a low overpotential of 233 mV at a current density of 10 mA cm–2, a low Tafel slope of 29.8 mV dec–1, and an excellent stability for over 500 h without any obvious structural destruction. This work demonstrates a facile one-step electrochemical metallurgical approach for fabricating self-supporting HEAs/MEAs electrocatalysts with nanosized surface for the application in water electrolysis.

Highly active polyethylene glycol grafted cellulose supported Pd nanoparticles for glucose electrooxidation

In this study, poly(ethylene glycol) (PEG) grafted cellulose (CE) composite catalyst support material (PEG-CE) was obtained by chemically cross-linking PEG at varying molecular weight and CE with isophorone diisocyanate (IPDI) and 2,4-toluylene diisocyanate (TDI). PEG-CE supported Pd (Pd/PEG-CE) catalyst was prepared by the chemical reduction method. The crystal size of the Pd/PEG-CE catalyst is 4.79 nm and its crystal structure has been determined to be face-centered cubic Pd. Elemental mapping results indicate that Pd was reduced onto PEG-CE successfully and uniformly. Pd exists in the elemental and Pd-O form in the catalyst system. The Pd loading rate of Pd/PEG-C_IPDI catalyst was determined as 18.8% by mass. Among the PEG-CEs prepared with TDI and IPDI, PEG4000-CE_TDI and PEG6000-CE_IPDI displayed the highest specific activities of 1.03 and 1.50 mA cm−2 for glucose electrooxidation. With Pd reduction on PEG4000-CE_TDI and PEG6000-CE_IPDI, the specific activities increased to 1.62 mA cm−2 and 6.97 mA cm‐2. Pd/PEG6000-CE_IPDI has the highest electrocatalytic activity and stability in this study for glucose electrooxidation and is an encouraging anode catalyst for direct glucose fuel cells.

Yttrium‐ and nitrogen‐doped NiCo phosphide nanosheets for high‐efficiency water electrolysis

AbstractEngineering high‐performance and low‐cost bifunctional catalysts for H2 (hydrogen evolution reaction [HER]) and O2 (oxygen evolution reaction [OER]) evolution under industrial electrocatalytic conditions remains challenging. Here, for the first time, we use the stronger electronegativity of a rare‐Earth yttrium ion (Y3+) to induce in situ NiCo‐layered double‐hydroxide nanosheets from NiCo foam (NCF) treated by a dielectric barrier discharge plasma NCF (PNCF), and then obtain nitrogen‐doped YNiCo phosphide (N‐YNiCoP/PNCF) after the phosphating process using radiofrequency plasma in nitrogen. The obtained N‐YNiCoP/PNCF has a large specific surface area, rich heterointerfaces, and an optimized electronic structure, inducing high electrocatalytic activity in HER (331 mV vs. 2000 mA cm−2) and OER (464 mV vs. 2000 mA cm−2) reactions in 1 M KOH electrolyte. X‐ray absorption spectroscopy and density functional theory quantum chemistry calculations reveal that the coordination number of CoNi decreased with the incorporation of Y atoms, which induce much shorter bonds of Ni and Co ions and promote long‐term stability of N‐YNiCoP in HER and OER under the simulated industrial conditions. Meanwhile, the CoN‐YP5 heterointerface formed by plasma N‐doping is the active center for overall water splitting. This work expands the applications of rare‐Earth elements in engineering bifunctional electrocatalysts and provides a new avenue for designing high‐performance transition‐metal‐based catalysts in the renewable energy field.

Synergistic effect of PDA and PVP on nanosized Pd doped graphite felt/Ni electrode for promoting the electrocatalytic degradation of 2,4- dichlorophenoxyacetic acid

Reducing the mass transfer barrier for the diffusion of water and pollutants to Pd sites is an important measure to achieve efficient degradation of chlorinated organic compounds. Herein, a simple electroless deposition method for preparing a superhydrophilic nanosized Pd-loaded graphite felt/Ni electrode with the aid of the dispersibility of polyvinylpyrrolidone (PVP) and adhesiveness of polydopamine (PDA) is proposed. The GF/Ni/PDA/Pd-PVP electrode exhibited high electrocatalytic activity toward 2,4-dichlorophenoxyacetic acid (2,4-D) under the optimized conditions, namely degradation and dechlorination efficiencies of 90.5% and 88.53%, respectively, corresponding to 39% higher than that on the GF/Ni/Pd electrode. Experimental results revealed that PDA and PVP doping enhanced the hydrophilicity of the electrode, promoted the dispersibility of Pd nanoparticles (NPs), and the formation of Pd (111) and Ni (111) crystal facets. Compared to the electron-deficient PVP, the appropriate electron-donating ability of PDA promoted the formation of a suitable ratio of electro-deficient and electron-rich Pd, thus enhancing the production of Hads* and C-Cl scission. Moreover, theoretical calculation indicated that the doping of PDA and PVP optimized the adsorption energies of 2,4-D, Hads*, and the main dechlorination product PA, which was obtained via 4-electron transfer via Hads*. Therefore, this study provides a simple and feasible way to fabricate an efficient cathode for 2,4-D dechlorination.

One-Dimensional High-Entropy Compounds.

One-dimensional (1D) high-entropy compounds (HECs) with subnano diameters are highly attractive because long-range electron delocalization may occur along the high-entropy atomic chain, which results in extraordinary properties. Nevertheless, synthesizing such 1D HECs presents a substantial challenge, and the physicochemical attributes of these novel structures remain ambiguous. Herein, we developed a comelting-filling-freezing-modification (co-MFFM) method for synthesizing 1D high-entropy metal phosphide (HEP) by simultaneously encapsulating various metal cations within single-walled carbon nanotubes (SWCNTs) followed with a phosphorization process. The resulting 1D HEP nanowires confined within SWCNTs exhibit crucial features, including an ultrafine, high-entropy, and amorphous structure, along with a core-shell arrangement. The SWCNT as a shell could donate π electrons to 1D HEP for enhanced electron delocalization and protect 1D HEP as an atomically single-layered protective covering, thus boosting high electrocatalytic activity and stability. Moreover, the co-MFFM method demonstrates scalability for mass production and displays universal applicability to the synthesis of various 1D HECs.

Deposition of FeOOH Layer on Ultrathin Hematite Nanoflakes to Promote Photoelectrochemical Water Splitting.

Hematite is one of the most promising photoanode materials for the study of photoelectrochemical (PEC) water splitting because of its ideal bandgap with sufficient visible light absorption and stability in alkaline electrolytes. However, owing to the intrinsically high electron-hole recombination, the PEC performance of hematite is still far below that expected. The efficient charge separation can be achieved via growth of FeOOH on hematite photoanode. In this study, hematite nanostructures were successfully grown on the surface of iron foil by the simple immersion deposition method and thermal oxidation treatment. Furthermore, cocatalyst FeOOH was successfully added to the hematite nanostructure surface to improve charge separation and charge transfer, and thus promote the photoelectrochemical water splitting. By utilizing the FeOOH overlayer as a cocatalyst, the photocurrent density of hematite exhibited a substantial 86% increase under 1.5 VRHE, while the onset potential showed an apparent shift towards the cathodic direction. This can be ascribed to the high reaction area for the nanostructured morphology and high electrocatalytic activity of FeOOH that enhanced the amount of photogenerated holes and accelerated the kinetics of water splitting.

Novel spinel based high entropy oxide as electrode for symmetric SOFCs

Fabrication of symmetric electrodes for intermediate temperature SOFCs can significantly reduce fuel cell production costs without compromising efficiency. Herein, we report a novel spinel based high entropy oxide (CuLiFeCoNi)1.4Mn1.6O4-δ (CM-HEO) that exhibit better symmetric electrode properties than the parent spinel oxide, Cu1.4Mn1.6O4-δ (CM). The prepared HEO exhibited good structural and thermal stability up to 800 °C as inferred from the XRD, Raman and TGA-DSC results. Temperature-programmed reduction and desorption profiles of CM-HEO outperformed CM by exhibiting hydrogen adsorption and lower CO2 desorption across different temperature ranges. The enhancement of Lewis acid-base sites is evident from the XPS analysis validating the observed increase in HOR and ORR activity. The high electrocatalytic activity of the material arise from its lower activation energies (0.27 eV in air, 0.09 eV in dry H2 and 0.03 eV in dry CH4) with a polarisation resistances of 0.152 Ωcm2 under ambient atmosphere and 0.044 Ωcm2 under dry H2. These findings exalt CM-HEO as an efficient symmetric SOFC electrode material.

Nb4C3Tx MXene-AgNPs decorated laser-induced graphene for selective detection of dopamine

In this study, a selective electrochemical sensor based on Nb4C3Tx MXene-silver nanoparticles (Nb4C3Tx MXene-AgNPs) decorated laser-induced graphene (LIG) electrode synthesized from flexible pyralux film was employed to detect dopamine (DA). The characterization of the synthesized LIG, Nb4C3Tx MXene, and AgNPs was conducted using UV–visible spectroscopy, scanning electron microscopy, and Raman spectroscopy. The electrochemical performance of the fabricated LIG electrode was enhanced from a peak anodic current (Ipa) of 150 μA to 330.4 μA upon modification with Nb4C3Tx MXene-AgNPs nanocomposite. The LIG- Nb4C3Tx MXene-AgNPs electrode exhibited high electrocatalytic activity toward the oxidation of DA via cyclic voltammetry and chronoamperometry techniques. The current response increased linearly with DA concentration and exhibited a wide linear range from 100 nM to 10 µM with a detection limit of 1 nM. The sensor also exhibited an excellent sensitivity of 160.96 μA/nM cm−2. Furthermore, the fabricated LIG-Nb4C3Tx MXene-AgNPs electrode showed excellent selectivity toward DA detection in the presence of common interfering compounds such as glucose, ascorbic acid, and uric acid and had high reproducibility. The developed LIG-Nb4C3Tx MXene-AgNPs flexible electrode platform is suitable for accurately and reliably detecting DA in the presence of competing analytes.

Efficient Counter Electrode of MoS2‐GO/PEDOT:PSS for Platinum‐free, High Performance Dye Sensitized Solar Cells

AbstractThe aim of this work is to fabricate the efficient platinum‐free counter electrodes for the development of advanced and high performance dye sensitized solar cells. MoS2‐GO/ PEDOT:PSS counter electrode has served as low‐cost, simple preparation and high efficient counter electrode for a DSSC. The Cyclic‐Voltammetry, electrochemical impedance spectroscopy and Tafel curve analysis indicate that the MoS2‐GO/PEDOT:PSS counter electrode possesses low charge transfer resistance on the electrolyte–electrode interface, high electrocatalytic activity and fast reaction kinetics for the reduction of tri‐iodide to iodide at the counter electrode. The DSSCs made with MoS2‐GO/PEDOT:PSS counter electrode achieve high power conversion efficiency of 7.73 % under standard light illumination of 100 mW/cm2, is higher than the platinum based counter electrode DSSC (5.53 %). The results witnessed the developed counter electrode is efficient and potential for platinum‐free dye sensitized solar cell applications.

CeO2-supported Pt nanoclusters for improved electrochemical oxidation of methanol

Developing highly durable and active Pt-supported catalysts is currently the most prominent and practicable electrocatalyst design strategy for direct methanol fuel cells (DMFC) due to their high electrocatalytic stability and activity. Herein, we fabricated CeO2 nanorods with tiny Pt nanoparticles that possess good electrocatalytic behavior for methanol oxidation reaction (MOR). In addition, the presence of Ce3+ and small Pt nanoparticles (3.46 nm) enhanced strong metal interaction, facilitating the formation of oxygen vacancies on the CeO2 surface to boost the MOR performance. Hence, the Pt-CeO2 catalyst revealed high mass activity (1414.0 mA mg−1) and areal-specific activity (1.615 mA cm−2) towards MOR in an acidic electrolyte, which was three times that of the 20% Pt/C catalyst (545.4 mA mg−1 and 0.856 mA cm−2). Besides, the Pt-CeO2 catalyst exhibited excellent performance of MOR in an alkaline electrolyte and retained 90.44% of its initial mass activity after 5000 cycles due to the unique morphology and synergistic effects between Pt and CeO2. Pt-CeO2 is regarded as a promising MOR electrocatalyst for DMFC applications.Graphical

Multivalent Sulfur Vacancy-Rich NiCo2 S4 @MnO2 Urchin-Like Heterostructures for Ambient Electrochemical N2 Reduction to NH3.

Innovative advances in the exploitation of effective electrocatalytic materials for the reduction of nitrogen (N2 ) to ammonia (NH3 ) are highly required for the sustainable production of fertilizers and zero-carbon emission fuel. In order to achieve zero-carbon footprints and renewable NH3 production, electrochemical N2 reduction reaction (NRR) provides a favorable energy-saving alternative but it requires more active, efficient, and selective catalysts. In current work, sulfur vacancy (Sv)-rich NiCo2 S4 @MnO2 heterostructures are efficaciously fabricated via a facile hydrothermal approach followed by heat treatment. The urchin-like Sv-NiCo2 S4 @MnO2 heterostructures serve as cathodes, which demonstrate an optimal NH3 yield of 57.31µgh-1 mgcat -1 and Faradaic efficiency of 20.55% at -0.2V versus reversible hydrogen electrode (RHE) in basic electrolyte owing to the synergistic interactionsbetween Sv-NiCo2 S4 and MnO2 . Density functional theory (DFT) simulation further verifies that Co-sites of urchin-like Sv-NiCo2 S4 @MnO2 heterostructures are beneficial to lowering the energy threshold for N2 adsorption and successive protonation. Distinctive micro/nano-architectures exhibit high NRR electrocatalytic activities that might motivate researchers to explore and concentrate on the development of heterostructures for ambient electrocatalytic NH3 generation.

Three-dimensional electrochemical Fenton degradation of CIP by doping Ce and Cu in Jacaranda shell base as particle electrodes

Currently, ciprofloxacin (CIP) in water environments has attracted wide attention. In order to degrade CIP by electrocatalysis, it is very important to develop catalysts with high catalytic activity as particle electrodes. In this study, Jacaranda shell was made into biochar (BC) by calcination, Ce and Cu modified BC (Ce-Cu/BC) was prepared by a simple impregnation and calcination method as a particle electrode in a three-dimensional electro-Fenton (3D/EF) system to degrade CIP. Characterization of the Ce-Cu/BC particle electrodes was conducted using SEM, XRD, and XPS, revealing the porous structure of the calcined jacaranda shell base, confirming successful loading of Ce and Cu. Optimal operating conditions for CIP removal were determined to be 4 g/100 mL particle electrodes dosage, initial pH of 5, 8 V voltage, and 2 mM Fe2+ concentration, resulting in a maximum CIP removal rate of 84.97% with an energy consumption of 1.32 W•h. Stability tests demonstrated the robustness of Ce-Cu/BC, while comparative tests and radical extinction experiments highlighted the high electrocatalytic activity of the 3D/EF system, primarily attributed to the indirect oxidation of •OH, an active substance generated within the system LC-MS and UV full-band scanning analyses were employed to propose potential CIP degradation pathways.

A Coordination-Derived Cerium-Based Amorphous-Crystalline Heterostructure with High Electrocatalytic Oxygen Evolution Activity.

The rational design of heterogeneous catalysts is crucial for achieving optimal physicochemical properties and high electrochemical activity. However, the development of new amorphous-crystalline heterostructures is significantly more challenging than that of the existing crystalline-crystalline heterostructures. To overcome these issues, a coordination-assisted strategy that can help fabricate an amorphous NiO/crystalline NiCeOx (a-NiO/c-NiCeOx ) heterostructure is reported herein. The coordination geometry of the organic ligands plays a pivotal role in permitting the formation of coordination polymers with high Ni contents. This consequently provides an opportunity for enabling the supersaturation of Ni in the NiCeOx structure during annealing, leading to the endogenous spillover of Ni from the depths of NiCeOx to its surface. The resulting heterostructure, featuring strongly coupled amorphous NiO and crystalline NiCeOx , exhibits harmonious interactions in addition to low overpotentials and high catalytic stability in the oxygen evolution reaction (OER). Theoretical calculations prove that the amorphous-crystalline interfaces facilitate charge transfer, which plays a critical role in regulating the local electron density of the Ni sites, thereby promoting the adsorption of oxygen-based intermediates on the Ni sites and lowering the dissociation-related energy barriers. Overall, this study underscores the potential of coordinating different metal ions at the molecular level to advance amorphous-crystalline heterostructure design.