Photocatalytic Oxygen Evolution with Prussain Blue Coated ZnO Origami Core-Shell Nanostructures.

The design and development of particulate photocatalysts has been an attractive strategy to incorporate earth-abundant metal ions to water splitting devices. Herein, we synthesized CoFe-Prussian blue (PB) coated ZnO origami core-shell nanostructures (PB@ZnO) with different mass ratio of PB components and investigated their photocatalytic water oxidation activities in the presence of an electron scavenger. Photocatalytic experiments reveal that the integration of PB on ZnO boosts the oxygen evolution rate by a factor of ~2.

Cyanide Linkage Isomerization Induced by Cobalt Oxidation-State Changes at a Co-Fe Prussian-Blue Analogue/ZnO Interface.

Understanding the interfacial composition in heterostructures is crucial for tailoring heterogenous electrochemical and photoelectrochemical processes. This work aims to elucidate the structure of a series of Co-Fe Prussian blue analogue modified ZnO (PBA/ZnO) electrodes with interface-sensitive vibrational sum frequency generation (VSFG) spectroscopy. Our measurements revealed, for the first time, a cyanide linkage isomerism at the PBA/ZnO interface, when the composite is fabricated at elevated temperatures.

Tunable Photocatalytic Activity of CoFe Prussian Blue Analogue Modified SrTiO Core-Shell Structures for Solar-Driven Water Oxidation.

This study presents a pioneering semiconductor-catalyst core-shell architecture designed to enhance photocatalytic water oxidation activity significantly. This innovative assembly involves the in situ deposition of CoFe Prussian blue analogue (PBA) particles onto SrTiO (STO) and blue SrTiO (bSTO) nanocubes, effectively establishing a robust p-n junction, as demonstrated by Mott-Schottky analysis. Of notable significance, the STO/PB core-shell catalyst displayed remarkable photocatalytic performance, achieving an oxygen evolution rate of 129.

3D-Cobalt-Dicyanamide-Derived 2D-Layered-Co(OH)-Based Catalyst for Light-Driven Hydrogen Evolution.

Derivation of 3D coordination polymers to produce active catalysts has been a feasible strategy to achieve a precise coordination sphere for the catalytic site. This study demonstrates the partial conversion of a 3D cobalt dicyanamide coordination polymer, Co-dca, to a 2D layered hydroxide-oxyhydroxide structure under photocatalytic conditions. The catalyst exhibits an activity as high as 28.

Rational design of an acceptor-chromophore-relay-catalyst tetrad assembly for water oxidation.

We report the step-by-step synthesis of a precious metal-free acceptor-chromophore-relay-catalyst tetrad assembly that exhibits a turnover frequency (TOF) of 7.5 × 10 s under neutral conditions. Transient absorption spectroscopic studies indicate that upon fullerenol incorporation into the investigated complexes, charge separation efficiency increases considerably.

Low-Pressure Deuterium Storage on Palladium-Coated Titanium Nanofilms: A Versatile Model System for Tritium-Based Betavoltaic Battery Applications.

Deuterium (D(g)) storage of Pd-coated Ti ultra-thin films at relatively low pressures is fine-tuned by systematically controlling the thicknesses of the catalytic Pd overlayer, underlying Ti ultra-thin film domain, D(g) pressure (), duration of D(g) exposure, and the thin film temperature. Structural properties of the Ti/Pd nanofilms are investigated via XRD, XPS, AFM, SEM, and TPD to explore new structure-functionality relationships. Ti/Pd thin film systems are deuterated to obtain a D/Ti ratio of up to 1.

Manipulating Intermetallic Charge Transfer for Switchable External Stimulus-Enhanced Water Oxidation Electrocatalysis.

Electrocatalytic processes involving the oxygen evolution reaction (OER) present a kinetic bottleneck due to the existence of linear-scaling relationships, which bind the energies of the different intermediates in the mechanism limiting optimization. Here, we offer a way to break these scaling relationships and enhance the electrocatalytic activity of a Co-Fe Prussian blue modified electrode in OER by applying external stimuli. Improvements of ≈11 % and ≈57 % were achieved under magnetic field (0.

A Dormant Reagent Reaction-Diffusion Method for the Generation of Co-Fe Prussian Blue Analogue Periodic Precipitate Particle Libraries.

Liesegang patterns that develop as a result of reaction-diffusion can simultaneously form products with slightly different sizes spatially separated in a single medium. We show here a reaction-diffusion method using a dormant reagent (citrate) for developing Liesegang patterns of cobalt hexacyanoferrate Prussian Blue analog (PBA) particle libraries. This method slows the precipitation reaction and produces different-sized particles in a gel medium at different locations.

Selective photocatalytic CO reduction by cobalt dicyanamide.

Photocatalytic conversion of CO into chemical fuels is a promising approach to tackle carbon emission and global warming. Herein, we promote a cobalt dicyanamide coordination compound, Co-dca, for the first time, as a selective catalyst to reduce CO to CO in the presence of a ruthenium photosensitizer (Ru PS) under visible light irradiation. Co-dca was prepared by a facile precipitation method and characterized by Infrared, UV-Vis, XRD, SEM, TEM, and XPS studies.

2D Network overtakes 3D for photocatalytic hydrogen evolution.

3-Dimensional (3D) cyanide coordination polymers, typically known as Prussian blue Analogues (PBAs), have received great attention in catalysis due to their stability, easily tuned metal sites, and porosity. However, their high crystallinities and relatively low number of surface-active sites significantly hamper their intrinsic catalytic activities. Herein, we report the utilization of a 2-dimensional (2D) layered cobalt tetracyanonickelate, [Co-Ni], for the reduction of protons to H.

Laser-ablation assisted strain engineering of gold nanoparticles for selective electrochemical CO reduction.

Strain engineering can endow versatile functions, such as refining d-band center and inducing lattice mismatch, on catalysts for a specific reaction. To this end, effective strain engineering for introducing strain on the catalyst is highly sought in various catalytic applications. Herein, a facile laser ablation in liquid (LAL) strategy is adopted to synthesize gold nanoparticles (Au NPs) with rich compressive strain (Au-LAL) for electrochemical CO reduction.

"Plug and Play" Photosensitizer-Catalyst Dyads for Water Oxidation.

We present a simple and easy-to-scale synthetic method to plug common organic photosensitizers into a cyanide-based network structure for the development of photosensitizer-water oxidation catalyst (PS-WOC) dyad assemblies for the photocatalytic water oxidation process. Three photosensitizers, one of which absorbs red light similar to P680 in photosystem II, were utilized to harvest different regions of the solar spectrum. Photosensitizers are covalently coordinated to CoFe Prussian blue structures to prepare PS-WOC dyads.

Light-Driven Water Oxidation with Ligand-Engineered Prussian Blue Analogues.

The elucidation of the ideal coordination environment of a catalytic site has been at the heart of catalytic applications. Herein, we show that the water oxidation activities of catalytic cobalt sites in a Prussian blue (PB) structure could be tuned systematically by decorating its coordination sphere with a combination of cyanide and bidentate pyridyl groups.  K[Co(bpy)][Fe(CN)] (), K[Co(phen)][Fe(CN)] (), {[Co(bpy)][Fe(CN)]}[Fe(CN)] (), and {[Co(phen)][Fe(CN)]}[Fe(CN)] Cl () were prepared by introducing bidentate pyridyl groups (phen: 1,10-phenanthroline, bpy: 2,2'-bipyridine) to the common synthetic protocol of Co-Fe Prussian blue analogues.

Electrodeposited cobalt hexacyanoferrate electrode as a non-enzymatic glucose sensor under neutral conditions.

A CoFe Prussian blue analogue (CoFe PB) modified FTO electrode, prepared via a facile electrodeposition method, is investigated as a non-enzymatic glucose sensor under neutral conditions. The electrode exhibits a linear detection of glucose in the 0.1-8.

Building an Iron Chromophore Incorporating Prussian Blue Analogue for Photoelectrochemical Water Oxidation.

Invited for the cover of this issue is the Ferdi Karadas and Ekmel Ozbay groups at Bilkent University and co-workers. The image presents an utopic city in Iron Age, which is powered by an iron photosensitizer that bridges semiconductor buildings (TiO nanowires) and the catalyst (cobalt site). Read the full text of the article at 10.

Building an Iron Chromophore Incorporating Prussian Blue Analogue for Photoelectrochemical Water Oxidation.

The replacement of traditional ruthenium-based photosensitizers with low-cost and abundant iron analogs is a key step for the advancement of scalable and sustainable dye-sensitized water splitting cells. In this proof-of-concept study, a pyridinium ligand coordinated pentacyanoferrate(II) chromophore is used to construct a cyanide-based CoFe extended bulk framework, in which the iron photosensitizer units are connected to cobalt water oxidation catalytic sites through cyanide linkers. The iron-sensitized photoanode exhibits exceptional stability for at least 5 h at pH 7 and features its photosensitizing ability with an incident photon-to-current conversion capacity up to 500 nm with nanosecond scale excited state lifetime.

Photocatalytic water oxidation with a Prussian blue modified brown TiO.

A recently emerging visible light-absorbing semiconductor, brown TiO (b-TiO), was coupled with a CoFe Prussian blue (PB) analogue to prepare an entirely earth-abundant semiconductor/water oxidation catalyst hybrid assembly. PB/b-TiO exhibits a sevenfold higher photocatalytic water oxidation activity compared to b-TiO. An elegant band alignment unified with the optical absorption of b-TiO and excellent electronic dynamics of PB yield a high-performance photocatalytic system.

How to Build Prussian Blue Based Water Oxidation Catalytic Assemblies: Common Trends and Strategies.

Prussian blue (PB) and its analogues (PBAs) have at least a three-century-long history in coordination chemistry. Recently, cobalt-based PBAs have been acknowledged as efficient and robust water oxidation catalysts. Given the flexibility in their synthesis, the structure and morphology of cobalt-based PBAs have been modified for enhanced catalytic activity under electrochemical (EC), photocatalytic (PC), and photoelectrochemical (PEC) conditions.

Precious Metal-Free Photocatalytic Water Oxidation by a Layered Double Hydroxide-Prussian Blue Analogue Hybrid Assembly.

The development of earth-abundant photocatalytic assemblies has been one of the bottlenecks for the advancement of scalable water splitting cells. In this study, a ZnCr layered double hydroxide and a CoFe Prussian blue analogue are combined to afford an earth-abundant photocatalytic assembly involving a visible light-absorbing semiconductor (SC) and a water oxidation catalyst (WOC). Compared to bare ZnCr-LDH, the SC-WOC hybrid assembly exhibits a threefold enhancement in photocatalytic activity, which is maintained for 6 h under photocatalytic conditions at pH 7.

Strong Light-Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO for Photoelectrochemical Water Splitting.

Invited for this month's cover is the group of Ferdi Karadas and Ekmel Ozbay at Bilkent University. The image proposes a hybrid architecture, in which the semiconductor photoactive host is coupled to a plasmonic particle and a catalyst, to significantly substantiate the photoactivity of the cell. The Full Paper itself is available at 10.

Strong Light-Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO for Photoelectrochemical Water Splitting.

A facial and large-scale compatible fabrication route is established, affording a high-performance heterogeneous plasmonic-based photoelectrode for water oxidation that incorporates a CoFe-Prussian blue analog (PBA) structure as the water oxidation catalytic center. For this purpose, an angled deposition of gold (Au) was used to selectively coat the tips of the bismuth vanadate (BiVO ) nanostructures, yielding Au-capped BiVO (Au-BiVO ). The formation of multiple size/dimension Au capping islands provides strong light-matter interactions at nanoscale dimensions.

A Robust, Precious-Metal-Free Dye-Sensitized Photoanode for Water Oxidation: A Nanosecond-Long Excited-State Lifetime through a Prussian Blue Analogue.

Herein, we establish a simple synthetic strategy affording a heterogeneous, precious metal-free, dye-sensitized photoelectrode for water oxidation, which incorporates a Prussian blue (PB) structure for the sensitization of TiO and water oxidation catalysis. Our approach involves the use of a Fe(CN) bridging group not only as a cyanide precursor for the formation of a PB-type structure but also as an electron shuttle between an organic chromophore and the catalytic center. The resulting hetero-functional PB-modified TiO electrode demonstrates a low-cost and easy-to-construct photoanode, which exhibits favorable electron transfers with a remarkable excited state lifetime on the order of nanoseconds and an extended light absorption capacity of up to 500 nm.

Visible light-driven water oxidation with a ruthenium sensitizer and a cobalt-based catalyst connected with a polymeric platform.

A facile synthesis for a photosensitizer-water oxidation catalyst (PS-WOC) dyad, which is connected through a polymeric platform, has been reported. The dyad assembly consists of a ruthenium-based chromophore and a cobalt-iron pentacyanoferrate coordination network as the water oxidation catalyst while poly(4-vinylpyridine) serves as the bridging group between two collaborating units. Photocatalytic experiments in the presence of an electron scavenger reveal that the dyad assembly maintains its activity for 6 h while the activity of a cobalt hexacyanoferrate and Ru(bpy)32+ couple decreases gradually and eventually decays after a 3 h catalytic experiment.