Single Ag Atoms Induce Ag-N/O Bonds on WO for Ultrastable Acid Ammonia Synthesis.

Ammonia from nitrate-containing wastewater demands the catalysts with high activity, stability, and selectivity toward acidic electrochemical nitrate reduction owing to the corrosion effect of the catalyst and the competitive hydrogen evolution reaction (HER). Herein, we synthesized single Ag atoms induced Ag-N/O bonds on one-dimensional WO nanowires for highly efficient and stable electrochemical nitrate reduction to ammonia under acidic conditions. The resultant catalyst achieved a Faradaic efficiency (FE) of ammonia exceeding ∼90% over a potential range of -0.

Direct ammonia and dihydroxyacetone production in an unbiased photoelectrochemical cell.

Photoelectrochemical production of ammonia usually suffers from a low solar-to-ammonia efficiency and a high overpotential, which influences the bias-free operation of sustainable photoelectrochemistry. Herein, we realize solar-driven ammonia production from waste nitrate by constructing copper-osmium catalysts deposited on the Sb(S,Se) semiconductor, enabling optimized photo-carrier transport pathways and a beneficial co-adsorption configuration of *NO-HO moieties. The photocathode reaches a photocurrent density of 5.

Electrochemical Nitrate Reduction to Ammonia on AuCu Single-Atom Alloy Aerogels under Wide Potential Window.

Electrocatalytic nitrate reduction to ammonia (NORR) is very attractive for nitrate removal and ammonia production in industrial processes. However, the nitrate reduction reaction is characterized by intense hydrogen competition at strong reduction potentials, which greatly limits the Faraday efficiency at strong reduction potentials. Herein, we reported an AuCu single-atom alloy aerogels (AuCu SAAs) with three-dimensional network structure with significant nitrate reduction performance of Faraday efficiency (FE) higher than 90 % over a wide potential range (0 ~ -1 V ).

Enhanced Charge Carrier Dynamics on Sb Se Photocathodes for Efficient Photoelectrochemical Nitrate Reduction to Ammonia.

Ammonia (NH ) is recognized as a transportable carrier for renewable energy fuels. Photoelectrochemical nitrate reduction reaction (PEC NO RR) offers a sustainable solution for nitrate-rich wastewater treatment by directly converting solar energy to ammonia. In this study, we demonstrate the highly selective PEC ammonia production from NO RR by constructing a CoCu/TiO /Sb Se photocathode.

Superhydrophilic CoFe Dispersion of Hydrogel Electrocatalysts for Quasi-Solid-State Photoelectrochemical Water Splitting.

Photoelectrochemical (PEC) water splitting is an attractive strategy to convert solar energy to hydrogen. However, the lifetime of PEC devices is restricted by the photocorrosion of semiconductors and the instability of co-catalysts. Herein, we report a feasible inherent cross-linking method for stabilizing semiconductors that uses a CoFe-dispersed polyacrylamide (PAM) hydrogel as a transparent protector.

Dynamic semiconductor-electrolyte interface for sustainable solar water splitting over 600 hours under neutral conditions.

Photoelectrochemical (PEC) water splitting that functions in pH-neutral electrolyte attracts increasing attention to energy demand sustainability. Here, we propose a strategy to in situ form a NiB layer by tuning the composition of the neutral electrolyte with the additions of nickel and borate species, which improves the PEC performance of the BiVO photoanode. The NiB/BiVO exhibits a photocurrent density of 6.

Bismuth atom tailoring of indium oxide surface frustrated Lewis pairs boosts heterogeneous CO photocatalytic hydrogenation.

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H and CO molecules and enable efficient gas-phase CO photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In ions in InO by single-site Bi ions, thereby enhancing the propensity to activate CO molecules.

Plasmonic Titanium Nitride Facilitates Indium Oxide CO Photocatalysis.

Nanoscale titanium nitride TiN is a metallic material that can effectively harvest sunlight over a broad spectral range and produce high local temperatures via the photothermal effect. Nanoscale indium oxide-hydroxide, In O (OH) , is a semiconducting material capable of photocatalyzing the hydrogenation of gaseous CO ; however, its wide electronic bandgap limits its absorption of photons to the ultraviolet region of the solar spectrum. Herein, the benefits of both nanomaterials in a ternary heterostructure: TiN@TiO @In O (OH) are combined.

Activation of α-Fe O for Photoelectrochemical Water Splitting Strongly Enhanced by Low Temperature Annealing in Low Oxygen Containing Ambient.

Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe O ) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe O is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.

Amorphous Mo-Ta Oxide Nanotubes for Long-Term Stable Mo Oxide-Based Supercapacitors.

With a large-scale usage of portable electric appliances, a high demand for increasingly high-density energy storage devices has emerged. MoO has, in principle, a large potential as a negative electrode material in supercapacitive devices due to high charge densities that can be obtained from its reversible redox reactions. Nevertheless, the extremely poor electrochemical stability of MoO in aqueous electrolytes prevents a practical use in high capacitance devices.

Anodic Titanium Dioxide Nanotubes for Magnetically Guided Therapeutic Delivery.

Hollow titanium dioxide (TiO) nanotubes offer substantially higher drug loading capacity and slower drug release kinetics compared to solid drug nanocarriers of comparable size. In this report, we load TiO nanotubes with iron oxide nanoparticles to facilitate site-specific magnetic guidance and drug delivery. We generate magnetic TiO nanotubes (TiONTs) by incorporating a ferrofluid containing Ø ≈ 10 nm iron oxide nanoparticles in planar sheets of weakly connected TiO nanotubes.

Spaced TiO Nanotubes Enable Optimized Pt Atomic Layer Deposition for Efficient Photocatalytic H Generation.

In the present work, we report the use of TiO nanotube (NT) layers with a regular intertube spacing that are decorated by Pt nanoparticles through the atomic layer deposition (ALD) of Pt. These Pt-decorated spaced (SP) TiO NTs are subsequently explored for photocatalytic H evolution and are compared to classical close-packed (CP) TiO NTs that are also decorated with various amounts of Pt by using ALD. On both tube types, by varying the number of ALD cycles, Pt nanoparticles of different sizes and areal densities are formed, uniformly decorating the inner and outer walls from tube top to tube bottom.

Spaced Titania Nanotube Arrays Allow the Construction of an Efficient N-Doped Hierarchical Structure for Visible-Light Harvesting.

Regularly spaced TiO nanotubes were prepared by anodizing a titanium substrate in triethylene glycol electrolyte at elevated temperature. In comparison to conventional TiO nanotubes, spaced nanotubes possess an adjustable spacing between the individual nanotubes; this allows for controlled buildup of a hierarchical nanoparticle-on-nanotube structure. Here, we use this principle for layer-by-layer decoration of the tubes with TiO nanoparticles.

Synthesis of free-standing TaN nanotube membranes and flow-through visible light photocatalytic applications.

We report on free-standing TaN nanotubular membranes with open top and bottom, used as visible-light-active, flow-through photocatalytic micro-reactors. We grow first a robust anodic TaO layer, lift-off a membrane and convert to TaN. Such membranes can easily, in a flow-through mode, degrade methylene blue under visible light (wavelength >400 nm) or solar illumination.

Photoelectrochemical H Generation from Suboxide TiO Nanotubes: Visible-Light Absorption versus Conductivity.

In the present work we report on the key factors dictating the photoelectrochemical (PEC) performance of suboxide titania (TiO ) nanotubes. TiO nanotubes were produced by a systematic variation of reduction heat treatments of TiO in Ar/H . The properties of the TiO tubes were investigated by electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid-state conductivity, reflectivity measurements, photocurrent spectroscopy, and photoelectrochemical hydrogen evolution.

Templated dewetting: designing entirely self-organized platforms for photocatalysis.

Formation and dispersion of metal nanoparticles on oxide surfaces in site-specific or even arrayed configuration are key in various technological processes such as catalysis, photonics, electrochemistry and for fabricating electrodes, sensors, memory devices, and magnetic, optical, and plasmonic platforms. A crucial aspect towards an efficient performance of many of these metal/metal oxide arrangements is a reliable fabrication approach. Since the early works on graphoepitaxy in the 70s, solid state dewetting of metal films on patterned surfaces has been much explored and regarded as a most effective tool to form defined arrays of ordered metal particles on a desired substrate.

Enhanced Solar Water Splitting by Swift Charge Separation in Au/FeOOH Sandwiched Single-Crystalline Fe O Nanoflake Photoelectrodes.

In this work, single crystalline α-Fe O nanoflakes (NFs) are formed in a highly dense array by Au seeding of a Fe substrate by a thermal oxidation technique. The NFs are conformally decorated with a thin FeOOH cocatalyst layer. Photoelectrochemical (PEC) measurements show that this photoanode, incorporating α-Fe O /FeOOH NFs rooted on the Au/Fe structure, exhibits significantly enhanced PEC water oxidation performance compared to the plain α-Fe O nanostructure on the Fe substrate.

Highly Conducting Spaced TiO Nanotubes Enable Defined Conformal Coating with Nanocrystalline Nb O and High Performance Supercapacitor Applications.

Establishing self-organized spacing between TiO nanotubes allows for highly conformal Nb O deposition that can be adjusted to optimized supercapacitive behavior.

Black Magic in Gray Titania: Noble-Metal-Free Photocatalytic H Evolution from Hydrogenated Anatase.

'Black' TiO -in the widest sense, TiO reduced by various treatments-has attracted tremendous scientific interest in recent years because of some outstanding properties; most remarkably in photocatalysis. While the material effects visible light absorption (the blacker, the better), black titania produced by high pressure hydrogenation was recently reported to show another highly interesting feature; noble-metal-free photocatalytic H generation. In a systematic investigation of high-temperature hydrogen treatments of anatase nanoparticles, TEM, XRD, EPR, XPS, and photoelectrochemistry are used to characterize different degrees of surface hydrogenation, surface termination, electrical conductivity, and structural defects in the differently treated materials.

Double-Side Co-Catalytic Activation of Anodic TiO Nanotube Membranes with Sputter-Coated Pt for Photocatalytic H Generation from Water/Methanol Mixtures.

Self-standing TiO nanotube layers in the form of membranes are fabricated by self-organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt-decorated membranes are transferred either in tube top-up or in tube top-down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H generation using either front or back-side light irradiation.

Aligned metal oxide nanotube arrays: key-aspects of anodic TiO nanotube formation and properties.

Over the past ten years, self-aligned TiO nanotubes have attracted tremendous scientific and technological interest due to their anticipated impact on energy conversion, environment remediation and biocompatibility. In the present manuscript, we review fundamental principles that govern the self-organized initiation of anodic TiO nanotubes. We start with the fundamental question: why is self-organization taking place? We illustrate the inherent key mechanistic aspects that lead to tube growth in various different morphologies, such as ripple-walled tubes, smooth tubes, stacks and bamboo-type tubes, and importantly the formation of double-walled TiO nanotubes versus single-walled tubes, and the drastic difference in their physical and chemical properties.

TiO nanotubes with laterally spaced ordering enable optimized hierarchical structures with significantly enhanced photocatalytic H generation.

In the present work we grow self-organized TiO nanotube arrays with a defined and controlled regular spacing between individual nanotubes. These defined intertube gaps allow one to build up hierarchical 1D-branched structures, conformally coated on the nanotube walls using a layer by layer nanoparticle TiO decoration of the individual tubes, i.e.

A Facile Surface Passivation of Hematite Photoanodes with Iron Titanate Cocatalyst for Enhanced Water Splitting.

The surface modification of semiconductor photoelectrodes with passivation overlayers has attracted great attention as an effective strategy to improve the charge separation and charge transfer processes across the semiconductor-electrolyte interface. In this work, a thin Fe2 TiO5 layer was decorated on nanostructured hematite nanoflake and nanocoral photoanodes (by thermal oxidation of iron foils) by a facile water-based solution method. Photoelectrochemical measurements show that the Fe2 O3 /Fe2 TiO5 heterostructure exhibits an obvious enhancement in photoelectrochemical water oxidation performance compared to the pristine hematite.