Co(OH)2 Nanoparticle-Encapsulating Conductive Nanowires Array: Room-Temperature Electrochemical Preparation for High-Performance Water Oxidation Electrocatalysis

Modulation of Molecular Spatial Distribution and Chemisorption with Perforated Nanosheets for Ethanol Electro-oxidation

Integrating thermodynamically favorable ethanol reforming reactions with hybrid water electrolysis will allow room-temperature production of high-value organic products and decoupled hydrogen evolution. However, electrochemical reforming of ethanol has not received adequate attention due to its low catalytic efficiency and poor selectivity, which are caused by the multiple groups and chemical bonds of ethanol. In addition to the thermodynamic properties affected by the electronic structure of the catalyst, the dynamics of molecule/ion dynamics in electrolytes also play a significant role in the efficiency of a catalyst. The relatively large size and viscosity of the ethanol molecule necessitates large channels for molecule/ion transport through catalysts. Perforated CoNi hydroxide nanosheets are proposed as a model catalyst to synergistically regulate the dynamics of molecules and electronic structures. Molecular dynamics simulations directly reveal that these nanosheets can act as a "dam" to enrich ethanol molecules and facilitate permeation through the nanopores. Additionally, the charge transfer behavior of heteroatoms modifies the local charge density to promote molecular chemisorption. As expected, the perforated nanosheets exhibit a small potential (1.39 V) and high Faradaic efficiency for the conversion of ethanol into acetic acid. Moreover, the concept in this work provides new perspectives for exploring other molecular catalysts.

Efficient, Full Spectrum-Driven H2 Evolution Z-Scheme Co2P/CdS Photocatalysts with Co-S Bonds

Exploring high-efficiency, low-cost, and stable photocatalysts that enable full solar spectrum including UV, visible, and near-infrared (NIR) light utilization for photocatalytic hydrogen generation still faces huge challenge. Herein, a Co₂P/CdS Z-scheme photocatalyst without a noble metal is rationally fabricated to achieve ultrabroad UV-vis-NIR harvesting. Compared to Pt/CdS, CdS, and Co₂P, the optimized Co₂P/CdS exhibits much more outstanding performance with the H₂ generation rates of 262.16, 66.98, and 3.93 mmol/g/h under solar, visible (780 nm > λ > 420 nm), and NIR (λ > 780 nm) light, respectively. Particularly, 10% Co₂P/CdS displays a prominent apparent quantum efficiency value of 2.26% at 700 nm. The Z-scheme transform route can effectively enhance the separation of charge carriers in Co₂P/CdS for UV-vis-driven HER, as confirmed by photoluminescence and photoelectrochemical measurements. More importantly, the Co-S bonds at the interface demonstrated by Fourier transform infrared, Raman (mapping), and X-ray photoelectron spectroscopy and density functional theory calculations can act as a "bridge" for charge transfer, thereby enhancing the full spectrum-driven H₂ evolution. To the best of our knowledge, this is a rare research on full spectrum-driven photocatalytic HER without a noble metal.

Iron-Salen Complex and Co2+ Ion-Derived Cobalt-Iron Hydroxide/Carbon Nanohybrid as an Efficient Oxygen Evolution Electrocatalyst

Metal-salen complexes are widely used as catalysts in numerous fundamental organic transformation reactions. Here, CoFe hydroxide/carbon nanohybrid is reported as an efficient oxygen evolution electrocatalyst derived from the in situ formed molecular Fe-salen complexes and Co2+ ions at a low temperature of 160 °C. It has been evidenced that Fe-salen as a molecular precursor facilitates the confined-growth of metal hydroxides, while Co2+ plays a critical role in catalyzing the transformation of organic ligand into nanocarbons and constitutes an essential component for CoFe hydroxide. The resulting Co1.2Fe/C hybrid material requires an overpotential of 260 mV at a current density of 10 mA cm-2 with high durability. The high activity is contributed to uniform distribution of CoFe hydroxides on carbon layer and excellent electron conductivity caused by intimate contact between metal and nanocarbon. Given the diversity of molecular precursors, these results represent a promising approach to high-performance carbon-based water splitting catalysts.

In situ growth of layered double hydroxides on boehmite AlOOH for active and stable oxygen evolution in alkaline media

Among all the non-precious electrocatalysts for the oxygen evolution reaction (OER), FeNi and FeCo layered double hydroxides (LDHs) display the best activity. However, due to the unavoidable transformation of the active M3+/4+ (M = Fe, Co, and Ni) ions into inert M-O-H species, their activity dramatically decreases after about 25 h during stability tests, which means the widely-adopted stability test with a duration of 24 h is not sufficient for LDHs. Herein, the in situ growth of Fe1Co1 and Fe1Ni1 LDH nanosheets on V- and Ni-doped AlOOH nanorods was extended for the duration of stable electrocatalysis to 50 h. The V and Ni dopants were found to promote the diffusion of active Fe, Co and Ni cations along the abundant {100} planes of AlOOH single-crystalline nanorods with their {100} family of crystal planes perpendicular to the lateral facet, avoiding the aggregation of the active species and their transformation into inert species and their following nucleation and growth. Besides, the nano-channels on the nanorods generated during the subsequent in situ growth of LDHs are beneficial for the supply of OH- and the transportation of O2, which enhance the activity and stability of these composites.

2D Free-Standing Nitrogen-Doped Ni-Ni3 S2 @Carbon Nanoplates Derived from Metal-Organic Frameworks for Enhanced Oxygen Evolution Reaction

2D metal-organic frameworks (2D MOFs) are promising templates for the fabrication of carbon supported 2D metal/metal sulfide nanocomposites. Herein, controllable synthesis of a newly developed 2D Ni-based MOF nanoplates in well-defined rectangle morphology is first realized via a pyridine-assisted bottom-up solvothermal treatment of NiSO₄ and 4,4'-bipyridine. The thickness of the MOF nanoplates can be controlled to below 20 nm, while the lateral size can be tuned in a wide range with different amounts of pyridine. Subsequent pyrolysis treatment converts the MOF nanoplates into 2D free-standing nitrogen-doped Ni-Ni₃ S₂ @carbon nanoplates. The obtained Ni-Ni₃ S₂ nanoparticles encapsulated in the N-doped carbon matrix exhibits high electrocatalytic activity in oxygen evolution reaction. A low overpotential of 284.7 mV at a current density of 10 mA cm^-2 is achieved in alkaline solution, which is among the best reported performance of substrate-free nickel sulfides based nanomaterials.

Two-Dimensional Zeolitic Imidazolate Framework-L-Derived Iron-Cobalt Oxide Nanoparticle-Composed Nanosheet Array for Water Oxidation

Rational design of various functional nanomaterials using MOFs as a template provides an effective strategy to synthesize electrocatalysts for water splitting. In this work, we reported that an iron-cobalt oxide with 2D well-aligned nanoflakes assembling on carbon cloth (Fe-Co₃O₄ NS/CC), fabricated by an anion-exchange reaction followed by an annealing process, could serve as a high-performance oxygen-evolving catalyst. Specifically, the zeolitic imidazolate framework-L-Co nanosheet array (ZIF-L-Co NS/CC) was synthesized through a facile ambient liquid-phase deposition reaction, and then reacted with [Fe(CN)₆]^3- ions as precursors during the anion-exchange reaction at room temperature. Finally, the Fe-Co₃O₄ NS/CC was obtained via annealing treatment. On account of the compositional and structural superiority, this 3D monolithic anode exhibited outstanding electrocatalytic performance with a low overpotential of 290 mV to obtain a geometrical current density of 10 mA cm^-2 and good durability for water oxidation in base.

Cu3N nanowire array as a high-efficiency and durable electrocatalyst for oxygen evolution reaction

Developing non-precious oxygen evolution reaction (OER) electrocatalysts with high performance and long-term stability has drawn considerable research interest in recent years. In this communication, we report a self-supported Cu3N nanowire array on copper foam (Cu3N NA/CF) which is derived from a Cu(OH)2 nanowire array on copper foam (Cu(OH)2 NA/CF) through a nitridation process. Intriguingly, this 3D electrode exhibits marvellous OER activity with the need of an overpotential of only 298 mV at a current density of 20 mA cm-2 in 1.0 M KOH. In addition, the obtained electrocatalyst is capable of maintaining its high performance for at least 25 h under a static current density of 20 mA cm-2.

High-performance N2-to-NH3 fixation by a metal-free electrocatalyst

The Haber-Bosch process for the synthesis of ammonia (NH3) not only causes large energy consumption but also leads to CO2 emissions. Electrocatalytic hydrogenation of N2 to NH3 under ambient conditions is a highly desirable alternative method; however, it needs an efficient electrocatalyst. In this study, we report a mesoporous boron nitride (MBN) metal-free electrocatalyst for the N2 reduction reaction under ambient conditions. Owing to its mesoporous structure, this MBN electrocatalyst can expose more active sites, resulting in an outstanding NH3 formation rate of 18.2 μg h-1 mgcat.-1 with a faradaic efficiency of 5.5% at -0.7 V vs. reversible hydrogen electrode in 0.1 M Na2SO4. It also demonstrates strong long-term electrochemical durability.

Synthesis of a MoS x -O-PtO x Electrocatalyst with High Hydrogen Evolution Activity Using a Sacrificial Counter-Electrode

Water splitting is considered to be a very promising alternative to greenly produce hydrogen, and the key to optimizing this process is the development of suitable electrocatalysts. Here, a sacrificial-counter-electrode method to synthesize a MoS x /carbon nanotubes/Pt catalyst (0.55 wt% Pt loading) is developed, which exhibits a low overpotential of 25 mV at a current density of 10 mA cm-2, a low Tafel slope of 27 mV dec-1, and excellent stability under acidic conditions. The theory calculations and experimental results confirm the high hydrogen evolution activity that is likely due to the fact that the S atoms in MoS x can be substituted with O atoms during a potential cycling process when using Pt as a counter-electrode, where the O atoms act as bridges between the catalytic PtO x particles and the MoS x support to generate a MoS x -O-PtO x structure, allowing the Pt atoms to donate more electrons thus facilitating the hydrogen evolution reaction process.

Manganese doped CdS sensitized graphene/Cu2MoS4 composite for the photoelectrochemical immunoassay of cardiac troponin I

As a newly emerged photoactive material, Cu₂MoS₄ has motivated wide research interests in the field of photoelectrochemistry. Based on manganese doped CdS (CdS:Mn) sensitized graphene (G)/Cu₂MoS₄ composite, we developed a label-free photoelectrochemical (PEC) immunosensor for the detection of cardiac troponin I (cTnI). G as an excellent 2D conductive material, combined with Cu₂MoS₄ could improve its charge transfer efficiency. CdS:Mn nanoparticles (NPs) loaded on G/Cu₂MoS₄ further enlarged the light absorption range of Cu₂MoS₄ and restrained the electron-hole pairs recombination. Under optimal conditions, the proposed PEC immunosensor responded sensitively to cTnI with a low detection limit of 0.18 pg/mL and a wide linear range (0.005-1000 ng/mL). Moreover, as-fabricated immunosensor also exhibited high sensitivity, excellent selectivity and good stability. This work also was extended to real samples analysis and obtained satisfied results.

MnCO3 as a New Electrochemiluminescence Emitter for Ultrasensitive Bioanalysis of β-Amyloid1-42 Oligomers Based on Site-Directed Immobilization of Antibody

In this work, an electrochemiluminescence (ECL) immunosensor utilizing MnCO₃ nanospheres as a novel ECL luminophor and the HWRGWVC (HC-7) heptapeptide as an efficient antibody capturer for site-directed immobilization with high affinity was proposed. MnCO₃ nanospheres prepared by a homogeneous precipitation method exhibited high ECL efficiency, low toxicity, favorable biocompatibility, and excellent stability. After the functionalization of polydimethyldiallylammonium chloride (PDDA), the obtained MnCO₃/PDDA could combine with gold nanoparticles (Au NPs) via electrostatic interaction (MnCO₃/PDDA/Au). Besides, HC-7 as a small peptide ligand has demonstrated an ability to bind the Fc portion of an antibody with high affinity. Because the end of HC-7 is a cysteine, it can connect to MnCO₃/PDDA/Au via a Au-S bond. Then, the antibody could be effectively captured by HC-7 through specific interaction with a better maintained activity than traditional coupling reaction. To verify the practicability of the constructed immunosensor, β-amyloid_1-42 oligomers (Aβ) were employed as an analyte. On the basis of the above points, the immunosensor performed favorable ECL property to Aβ concentrations in a wide linear range (0.1 pg/mL to 10 ng/mL) with a low detection limit (19.95 fg/mL). With excellent repeatability, selectivity, and stability, this method opened up a new avenue for realizing the ultrasensitive detection of Aβ and other biomarkers in a real sample analysis.

Liquid-exfoliation of S-doped black phosphorus nanosheets for enhanced oxygen evolution catalysis

Black phosphorus (BP) has recently drawn great attention in the field of electrocatalysis due to its distinct electrocatalytic activity for the oxygen evolution reaction (OER). However, the slow OER kinetics and the poor environmental stability of BP seriously limits its overall OER performance and prevents its electrocatalysis application. Here, sulfur (S)-doped BP nanosheets, which are prepared using high-pressure synthesis followed by liquid exfoliation, have been demonstrated to have much better OER electrocatalytic activity and environmental stability compared to their undoped counterparts. The S-doped BP nanosheets display a Tafel slope of 75 mV dec^-1, which is a favorable value refered to the kinetics of OER in electrochemical tests. Notably, there is no degradation of S-doped BP nanosheets after six days exposure to ambient, indicating an excellent environmental stability of the S-doped BP. The density functional theory calculations show that the OER activity of BP originate from its crystal defects and heteroatom S doping can effectively enhance its OER activity and stability. These results highlight the doping effect on electrocatalytic activities and stability of BP and provide a simple and effective method to design highly efficient OER catalysts based on the modification of BP.

Morphology-controlled synthesis of CoMoO4 nanoarchitectures anchored on carbon cloth for high-efficiency oxygen oxidation reaction

Novel CoMoO₄ nanoarrays with different morphologies are anchored on a carbon cloth via a simple hydrothermal method by adjusting the Co/Mo atom ratio. The in situ growth and tight immobilization of the CoMoO₄ nanocomposite on the carbon cloth can facilitate the electrolyte infiltration and electrons transfer rate at the contact interface. Therefore, the free-standing electrode of CoMoO₄/carbon cloth with interconnected nanosheets shows superior electrocatalytic activity, and the overpotential of 286 mV is obtained at 15 mA cm⁻² in alkaline solution. Moreover, the catalyst also exhibits a small Tafel slope of 67 mV dec⁻¹ as well as good stability. The relationship between the active material morphology, contact interface and the electrocatalytic performance is also discussed. As the carbon cloth is commercially available, this simple but effective structural controlling method demonstrates a new large-scale practical electrode fabrication technique for high performance OER electrodes and large-scale water splitting.

Novel CoMoO₄ nanoarrays with different morphologies are anchored on a carbon cloth via a simple hydrothermal method by adjusting the Co/Mo atom ratio.

A universal and controllable strategy of constructing transition-metal nitride heterostructures for highly enhanced bifunctional electrocatalysis

A family of transition-metal nitride heterostructures were synthesized by a universal and controllable method to remedy the drawbacks of ordinary bifunctional electrocatalysts.

Three-dimensional interconnected Co(OH)2 nanosheets on Ti mesh as a highly sensitive electrochemical sensor for hydrazine detection

Three-dimensional interconnected Co(OH)₂ nanosheets on TM, prepared by low cost and simple electrodeposition method, exhibit highly sensitive electrochemical hydrazine detection.

Robust and superwetting island-shaped phytate bimetallic oxyhydroxide porous nanoclusters via a mild self-assembly—etching–catching—electrochemical oxidization strategy for an enhanced oxygen evolution reaction

Robust and superwetting island-shaped PBMO porous nanoclusters via a mild self-assembly—etching–catching—electrochemical oxidization strategy for an enhanced OER.

Room temperature thiosulfate ion redox reaction-driven synthesis of a robust porous copper–cobalt–sulfur–oxygen nanowire coating on copper foam for highly-efficient and low-cost oxygen evolution reaction

Room temperature thiosulfate ion redox reaction-driven synthesis of robust porous Cu–Co–S–O NWC on copper foam for highly-efficient and low-cost OER.

A novel FeS–NiS hybrid nanoarray: an efficient and durable electrocatalyst for alkaline water oxidation

A novel FeS–NiS/TM nanosheet array was developed for alkaline OER; this catalyst only requires an overpotential of 260 mV to afford a current density of 10 mA cm⁻² in 1.0 M KOH.

Concentrated-acid triggered superfast generation of porous amorphous cobalt oxide toward efficient water oxidation catalysis in alkaline solution

Amorphous cobalt oxide on carbon cloth (AMO-CoO/CC) was prepared as an excellent water-oxidation catalyst with 50 mV less overpotential at 10 mA cm⁻² than highly-crystallized Co₃O₄ in 1.0 M KOH.

Amorphous Ni–Fe double hydroxide hollow nanocubes enriched with oxygen vacancies as efficient electrocatalytic water oxidation catalysts

A hollow nanocube Ni_0.75Fe_0.25(OH)_x exhibits good oxygen evolution activity, which should be attributed to electronic modulation and abundant oxygen vacancies.

Ultra-small Mo2N on SBA-15 as a highly efficient promoter of low-loading Pd for catalytic hydrogenation

Decreasing Pd usage whilst maintaining a superior performance is promising, but remains a challenge in the catalytic field. Herein, we have demonstrated the highly efficient promotion of Mo₂N with a reduced amount of Pd for the liquid-phase hydrogenation reaction. The Mo₂N (2-3 nm) was uniformly anchored onto mesoporous SBA-15 by using PMo₁₂ as the Mo source. The small size and good dispersion of Mo₂N is favourable for allowing their effective contact with post-loading Pd. This good contact is conducive to developing a synergistic catalyst, which was verified by studying the liquid-phase hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) with NaBH₄ as the H source. The conversion ability of PNP to PAP on 1 wt% Pd-Mo₂N/SBA-15 was vastly superior to 1 wt% Pd/SBA-15 and even better than 20 wt% Pd/SBA-15. The low-Pd, highly efficient catalysis is ascribed to the transfer of the electrons from Mo₂N to Pd for the easy activation of H. The synergy can be affected by the type of support used. SBA-15 is superior to SiO₂ and the other supports, which could be related to the large surface area and the plentiful number of pores on SBA-15, which is favourable to the dispersion of Pd and Mo₂N, and the transfer/diffusion of the reactants. In particular, a highly efficient catalyst can be achieved at an even more reduced Pd loading (0.05 wt%). The current method describes the design of a highly efficient catalyst for the hydrogenation reaction using low amounts of noble metals.

Dual-Mode Electrochemical Immunoassay for Insulin Based on Cu7S4-Au as a Double Signal Indicator

The detection of insulin by electrochemical (EC) immunoassay is desirable but highly challenged due to the obstacle of improving its accuracy, especially in a single-response system. In this work, based on Cu₇S₄-Au as a dual signal indicator, we fabricated a dual-mode electrochemical immunoassay for insulin. Especially, Cu₇S₄ presents a strong differential pulse voltammetry (DPV) signal for the electron transfer between Cu²⁺ and Cu⁺, without the addition of K₃[Fe(CN)₆] or other electron transfer mediators. Furthermore, Cu₇S₄ displays high sensitivity and high electrocatalytic activity toward the reduction of H₂O₂ through chronoamperometry (CA). The introduction of Au nanoparticles can not only link on the surface of Cu₇S₄ by the chemical bond of Au-SH, but also connect the second antibody (Ab₂) by the chemical bond of Au-N. Due to the superior electroconductivity of Au nanoparticles and the synergistic effect between the Au nanoparticles and Cu₇S₄, a high sensitivity is achieved by means of DPV and CA. To improve the loading capacity of antibodies, nanofiber polyaniline covalently grafted graphene (GS-PANI) linked with Au nanoparticles (GS-PANI-Au) as the matrix material was prepared. Based on Cu₇S₄-Au as a double signal indicator, the developed EC immunoassay for insulin exhibits a wide linear response for insulin detection in the range from 0.1 pg/mL to 50 ng/mL, with a low detection limit of 35.8 and 12.4 fg/mL through DPV and CA modes, respectively. Furthermore, the immunosensor displays an excellent analytical capability for insulin and promises application in quantitative detection of other disease markers in clinical diagnosis.

Hierarchical Cobalt Borate/MXenes Hybrid with Extraordinary Electrocatalytic Performance in Oxygen Evolution Reaction

Oxygen evolution reaction (OER) is a key reaction for many renewable energy storage and conversion techniques. Developing efficient non-precious metal-based electrocatalysts for OER has attracted increasing attention. Herein is reported a strategy to fabricate hierarchical cobalt borate/Ti₃ C₂ T_x MXene (Co-B_i /Ti₃ C₂ T_x ) hybrid through fast chemical reactions at room temperature. This interesting hierarchical structure of Co-B_i /Ti₃ C₂ T_x hybrid is beneficial for exposing more active sites, improving mass diffusion, and charge-transfer pathways for electrochemical reaction. Moreover, a strong interaction between Co-B_i and Ti₃ C₂ T_x ensures efficient charge transfer and facilitates the electrostatic attraction of more anionic intermediates for a fast redox process. Consequently, the hierarchical Co-B_i /Ti₃ C₂ T_x hybrid shows extraordinary OER catalytic activity to deliver a current density of 10 mA cm^-2 at an overpotential of 250 mV, and a Tafel slope of about 53 mV dec^-1 .

Exciton energy transfer-based fluorescent sensor for the detection of Hg2+ through aptamer-programmed self-assembly of QDs

Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg²⁺ has been designed through DNA aptamer-programmed self-assembly of CdTe quantum dots (QDs). In this work, CdTe QDs were applied as fluorescence signal source. The two pieces of T-rich aptamer played a role as molecular recognition probes which could bind to the target Hg²⁺ specifically. The extent of Hg²⁺-triggered self-assembly of QDs depended on the concentration of Hg²⁺, which resulted in an exciton energy transfer effect between QDs, giving an obvious fluorescence signal decrease and red-shift of the fluorescent peak. Based on this principle, we could detect the Hg²⁺ in two different signal modes. The limit of detection (LOD) was 3.33 nM. The proposed sensing method exhibited its application in detecting Hg²⁺ in real water samples with satisfactory performance. The results indicated that this proposed sensor will be of great potential in biological and analytical fields.

Metal-Organic Framework-Derived Co3O4/Au Heterostructure as a Catalyst for Efficient Oxygen Reduction

Porous nanostructures with a yolk-shell complex interior will provide lots of virtues to construct advanced catalysts. In our work, the preparation of novel yolk-shell Au nanocrystal-loaded Co₃O₄ nanocages (Co₃O₄/Au heterostructure) from a metal-organic framework-derived composite was reported. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and so forth were used to analyze the morphology, structure, and composition of the heterostructures. Most importantly, Co₃O₄/Au heterostructures are a kind of low-cost, good performance catalysts for the oxygen reduction reaction to replace the noble-Pt catalysts. The high surface area of the porous structure and the excellent electron transfer properties of well-dispersed Au nanocrystals and also the electronic coupling effect between Co₃O₄ and Au in the composites are attributed to the good performance.

Highly stable photoelectrochemical cells for hydrogen production using a SnO2-TiO2/quantum dot heterostructured photoanode

Photoelectrochemical (PEC) water splitting implementing colloidal quantum dots (QDs) as sensitizers is a promising approach for hydrogen (H2) generation, due to the QD's size-tunable optical properties. However, the challenge of long-term stability of the QDs is still unresolved. Here, we introduce a highly stable QD-based PEC device for H2 generation using a photoanode based on a SnO2-TiO2 heterostructure, sensitized by CdSe/CdS core/thick-shell "giant" QDs. This hybrid photoanode architecture leads to an appreciable saturated photocurrent density of ∼4.7 mA cm-2, retaining an unprecedented ∼96% of its initial current density after two hours, and sustaining ∼93% after five hours of continuous irradiation under an AM 1.5G (100 mW cm-2) simulated solar spectrum. Transient photoluminescence (PL) measurements demonstrate that the heterostructured SnO2-TiO2 photoanode exhibits faster electron transfer compared with the bare TiO2 photoanode. The lower electron transfer rate in the TiO2 photoanode can be attributed to slow electron kinetics in the ultraviolet regime, revealed by ultrafast transient absorption spectroscopy. Graphene microplatelets were further introduced into the heterostructured photoanode, which boosted the photocurrent density to ∼5.6 mA cm-2. Our results demonstrate that the SnO2-TiO2 heterostructured photoanode holds significant potential for developing highly stable PEC cells.

Phase-selective synthesis of self-supported RuP films for efficient hydrogen evolution electrocatalysis in alkaline media

Large-scale hydrogen production through alkaline water electrolysis requires highly active and less expensive materials to replace platinum as a catalyst for the hydrogen evolution reaction (HER). Ruthenium, as the cheapest platinum-group element, has recently been demonstrated to exhibit excellent activity toward the HER. However, achieving better HER activity of ruthenium-based materials by selecting a more active phase is still unexplored. Herein, we report the fabrication of self-supported RuP and RuP₂ catalyst films on carbon cloth (RuP/CC and RuP₂/CC) via a facile, potentially scalable, and phase-controllable synthetic method. RuP/CC displays superior catalytic activity with a low overpotential of 13 mV at 10 mA cm^-1, outperforming RuP₂/CC (33 mV at 10 mA cm^-1) and most non-Pt HER catalysts. Moreover, good electrochemical stability and faradaic efficiency of nearly 100% are also demonstrated for RuP/CC. Density functional theory calculations reveal that RuP with a higher charge density at the Ru site is more favorable for the chemisorption of hydrogen, thereby exhibiting better HER activity than RuP₂.

Boosting water oxidation electrocatalysts with surface engineered amorphous cobalt hydroxide nanoflakes

Enriching dominant active intermediates is most pivotal in developing efficient non-noble oxygen evolution reaction (OER) electrocatalysts for water oxidation. Herein, we report surface-engineered amorphous cobalt hydroxide nanoflakes on nickel foam as highly active electrocatalysts for boosting water oxidation by a new repeatedly switching current-polarity strategy. It is discovered that sulfur introduction can simultaneously increase the Co3+/Co2+ ratio to generate more targeted OOH* intermediates and regulate the surface electronic structure to greatly boost its intrinsic activity. The density functional theory (DFT) calculations further confirm the reduction of the free energy of the OOH* intermediates. Consequently, our Co(OH)xS electrocatalyst exhibits an ultralow overpotential of 283 and 365 mV at 100 and 1000 mA cm-2 in alkaline media, respectively, and its turnover frequency (TOF) is more than 4 times higher than the corresponding Co(OH)x catalysts. This heteroatom triggered surface engineering may open up avenues to explore other efficient non-noble metal electrocatalysts for water oxidation.

Conductive Leaflike Cobalt Metal-Organic Framework Nanoarray on Carbon Cloth as a Flexible and Versatile Anode toward Both Electrocatalytic Glucose and Water Oxidation

Transition metal-organic frameworks (MOFs), on account of their unique inherent properties of large pore volume, high specific surface area, tunable pores, and good catalytic activity, have been highly regarded as superior catalysts recently for water electrolysis, supercapacitors, batteries, sensors, and so on. Herein, we report on a cobalt MOF phase with 3D well-aligned nanosheets array architecture on carbon cloth (Co-MOF NS/CC), fabricated by a facile ambient liquid-phase deposition, could serve as a self-standing Janus catalytic electrode toward both glucose and water oxidation. It shows good glucose-sensing performance with low determination limit and large detection range. Also, it exhibits high water-oxidation efficiency with low overpotential and good durability. This work demonstrates the potential of utilizing transition-metal based well-aligned MOF nanoarrays for electrocatalytic oxidation.

CoC2O4·2H2O derived Co3O4 nanorods array: a high-efficiency 1D electrocatalyst for alkaline oxygen evolution reaction

Self-standing Co₃O₄ nanorods array on Co foil as a 1D OER catalyst electrode, only needs overpotential of 308 mV to drive 15 mA cm⁻² in 1.0 M KOH, with good long-term electrochemical durability and a high turnover frequency.

Porous Fe–N-codoped carbon microspheres: an efficient and durable electrocatalyst for oxygen reduction reaction

Porous Fe–N-codoped carbon microspheres act as an efficient and stable electrocatalyst for ORR.

Cr2O3 nanofiber: a high-performance electrocatalyst toward artificial N2 fixation to NH3 under ambient conditions

Cr₂O₃ nanofiber acts as a superb electrocatalyst for artificial N₂ fixation, showing excellent selectivity and durability under ambient conditions.

Ultra-thin wrinkled NiOOH–NiCr2O4 nanosheets on Ni foam: an advanced catalytic electrode for oxygen evolution reaction

NiOOH–NiCr₂O₄/NF shows high activity for the OER in alkaline media, achieving a catalytic current density of 20 mA cm⁻² at an overpotential of 271 mV.