Extended π-conjugative n-p type homostructural graphitic carbon nitride for photodegradation and charge-storage applications

Ligand-triggered antenna effect and dual emissions in Eu(III) MOF and its application in multi-mode sensing of 1,4-dioxane

A new set of metal-organic frameworks was designed by functionalizing g-C3N4 with benzoic acid and using them as structure-directing ligands during the metal-organic framework (MOF) formation. One such MOF exhibited dual emissions, both metal- and ligand-centered, enabling ratiometric sensing of the carcinogenic industrial solvent dioxane. The fabricated MOFs possessed a unique fluffy spherical morphology that enabled atomic level resolution in transmission electron microscopy-a rarity in MOFs due to the 'Knock-on' effect. Sensor experiments showed a rapid response within 5 s of analyte introduction and achieved a low limit of detection (LOD) of 0.026 ppm, well below the FDA-approved level of 10 ppm. In addition, the sensor exhibited exceptional selectivity, discriminating 1,4-dioxane from a pool of 16 solvents. This increased sensing capability was attributed to the formation of complexes and precise alignment of energy levels between the host and analyte, facilitating photoinduced electron transfer (PET). This material is equally efficient for colorimetric detection of the same solvent under excitation of UV light as well as gas phase detection of this volatile organic compound through I-V characteristics. Density functional theory (DFT) analysis supported the crucial role of Eu and the ligand system in efficiently detecting 1,4-dioxane by fluorescence spectroscopy, as shown in the energy level diagram. Future research could focus on optimizing these metal-organic frameworks for enhanced industrial applications in the detection of dioxane and exploring their potential applications in real-world environmental monitoring and public health safety.

Epitaxial Growth of a Three-Dimensional Hollow and Chestnut Shell Photothermal p-n Junction Photoanode

The p-n junction, a widely studied semiconductor material structure, offers only limited improvements in photoelectrochemical (PEC) efficiency. Herein, a three-dimensional (3D) p-n junction h-Ta3N5@CoN featuring a stable chestnut shell hollow sphere structure and photothermal effect was synthesized by using an epitaxial growth strategy. The fine fibers within the sphere induce Rayleigh scattering, which scatters unabsorbed light, thereby enabling secondary absorption and enhancing light utilization. The quantum confinement effects generated by CoN fine fibers, which are sized in a few nanometers, inhibit the recombination of electron-hole pairs. Moreover, the lattice matching between Ta3N5 and CoN allows for smoother movement of carriers and nonradiative relaxation phonons along the lattice, thereby enhancing the transport of both carriers and heat. The obtained h-Ta3N5@CoN/FTO p-n junction photoanode, under near-infrared (NIR) auxiliary irradiation, demonstrates a photocurrent of 8.71 mA cm-2 at 1.23 VRHE. Moreover, the h-Ta3N5@CoN+NIR/FTO photoanode can sustain operation for 168 h, which, to my knowledge, surpasses the operational durations of all other Ta3N5-based photoanodes. This study synthesizes three-dimensional hollow chestnut shell photothermal p-n heterojunctions through an epitaxial growth strategy, endowing the material with a more efficient carrier separation and photothermal transfer efficiency.

Flexible Triboelectric Nanogenerators based on Hydrogel/g-C3N4 Composites for Biomechanical Energy Harvesting and Self-Powered Sensing

Flexible and stretchable triboelectric nanogenerators (TENGs) have been rapidly advanced owing to the demand for portable and wearable electronic devices that can work under universal or motional circumstances. While versatile materials can be applied in a TENG as dielectric materials, flexible and cost-effective electrodes are crucially important for the output performance of TENGs. Herein, we developed a poly(vinyl alcohol) (PVA) hydrogel TENG doped with a novel two-dimensional material, graphitic carbon nitride (g-C3N4), which could act as both a cost-effective flexible electrode and a positive dielectric for TENG with different morphologies. The measured peak-to-peak open-circuit voltage of the TENG reached 80 V at a dopant concentration of 2.7 wt % in single-electrode mode, which is far higher than that of the pristine PVA hydrogel TENG. As a demonstration of the application, the g-C3N4/PVA hydrogel TENG can be adopted as electronic skin to monitor the movement of the human body. Low-frequency mechanical energy-harvesting devices in different morphologies including discoid flake shape, tube shape, and spiral shape in the single-electrode mode or contact-separation mode have been designed, fabricated, and evaluated. All of these merits of the proposed hydrogel TENG after doping two-dimensional (2D) material g-C3N4 have demonstrated their promising potential for versatile applications in biomechanical energy harvesting and self-powered sensing.

Synthesis and up-to-date applications of 2D microporous g-C3N4 nanomaterials for sustainable development

In recent years, with the development of industrial technology and the increase of people's environmental awareness, the research on sustainable materials and their applications has become a hot topic. Among two-dimensional (2D) materials that have been selected for sustainable research, graphitic phase carbon nitride (g-C3N4) has become a hot research topic because of its many outstanding advantages such as simple preparation, good electrochemical properties, excellent photochemical properties, and better thermal stability. Nevertheless, the inherent limitations of g-C3N4 due to its relatively poor specific surface area, rapid charge recombination, limited light absorption range, and inferior dispersion in aqueous and organic media have limited its practical application. In the review, we summarize and analyze the unique structure of the 2D microporous nanomaterial g-C3N4, its synthesis method, chemical modification method, and the latest application examples in various fields in recent years, highlighting its advantages and shortcomings, with a view to providing ideas for overcoming the difficulties in its application. Furthermore, the pressing challenges faced by g-C3N4 are briefly discussed, as well as an outlook on the application prospects of g-C3N4 materials. It is expected that the review in this paper will provide more theoretical strategies for the future practical application of g-C3N4-based materials, as well as contributing to nanomaterials in sustainable applications.

Coordination Engineering of Dual Co, Ni Active Sites in N-Doped Carbon Fostering Reversible Oxygen Electrocatalysis

The development of affordable and non-noble-metal-based reversible oxygen electrocatalysts is required for renewable energy conversion and storage systems like metal-air batteries (MABs). However, the nonbifunctionality of most of the catalysts impedes their use in rechargeable MAB applications. Moreover, the loss of active sites also affects the long-term performance of the electrocatalyst toward oxygen electrocatalysis. In this work, we report a simplistic yet controllable chemical approach for the synthesis of dual transitional metals such as cobalt, nickel, and nitrogen-doped carbon (CoNi-NC) as bifunctional electrode materials for rechargeable zinc-air batteries (ZABs). The spatially isolated Ni-N4 and Co-N4 active units were rendered for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. The individual efficacy of both reversible reactions enables an ΔE value of ∼0.72 V, which outperforms several bifunctional electrocatalysts reported in the literature. The half-wave potential (E1/2) and overpotential were achieved at 0.83 V and 330 mV (vs RHE) for ORR and OER, respectively. The peak power density of ZAB equipped with the CoNi-NC catalyst was calculated to be 194 mW cm-2. The present strategy for the synthesis of bifunctional electrocatalysts with dual active sites offers prospects for developing electrochemical energy storage and conversion systems.

Simultaneously Achieving Fast Intramolecular Charge Transfer and Mass Transport in Holey D-π-A Organic Conjugated Polymers for Highly Efficient Photocatalytic Pollutant Degradation

Simultaneously realizing efficient intramolecular charge transfer and mass transport in metal-free polymer photocatalysts is critical but challenging for environmental remediation. Herein, we develop a simple strategy to construct holey polymeric carbon nitride (PCN)-based donor-π-acceptor organic conjugated polymers via copolymerizing urea with 5-bromo-2-thiophenecarboxaldehyde (PCN-5B2T D-π-A OCPs). The resultant PCN-5B2T D-π-A OCPs extended the π-conjugate structure and introduced abundant micro-, meso-, and macro-pores, which greatly promoted intramolecular charge transfer, light absorption, and mass transport and thus significantly enhanced the photocatalytic performance in pollutant degradation. The apparent rate constant of the optimized PCN-5B2T D-π-A OCP for 2-mercaptobenzothiazole (2-MBT) removal is ∼10 times higher than that of the pure PCN. Density functional theory calculations reveal that the photogenerated electrons in PCN-5B2T D-π-A OCPs are much easier to transfer from the donor tertiary amine group to the benzene π-bridge and then to the acceptor imine group, while 2-MBT is more easily adsorbed on π-bridge and reacts with the photogenerated holes. A Fukui function calculation on the intermediates of 2-MBT predicted the real-time changing of actual reaction sites during the entire degradation process. Additionally, computational fluid dynamics further verified the rapid mass transport in holey PCN-5B2T D-π-A OCPs. These results demonstrate a novel concept toward highly efficient photocatalysis for environmental remediation by improving both intramolecular charge transfer and mass transport.

Mitigating phytotoxicity of tetracycline by metal-free 8-hydroxyquinoline functionalized carbon nitride photocatalyst

Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride (TCH) over a metal-free 8-hydroxyquinoline (8-HQ) functionalized carbon nitride (CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth. This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.

Fast light-switchable polymeric carbon nitride membranes for tunable gas separation

Switchable gas separation membranes are intriguing systems for regulating the transport properties of gases. However, existing stimuli-responsive gas separation membranes suffer from either very slow response times or require high energy input for switching to occur. Accordingly, herein, we introduced light-switchable polymeric carbon nitride (pCN) gas separation membranes with fast response times prepared from melamine precursor through in-situ formation and deposition of pCN onto a porous support using chemical vapor deposition. Our systematic analysis revealed that the gas transport behavior upon light irradiation is fully governed by the polarizability of the permeating gas and its interaction with the charged pCN surface, and can be easily tuned either by controlling the power of the light and/or the duration of irradiation. We also demonstrated that gases with higher polarizabilities such as CO2 can be separated from gases with lower polarizability like H2 and He effectively with more than 22% increase in the gas/CO2 selectivity upon light irradiation. The membranes also exhibited fast response times (<1 s) and can be turned “on” and “off” using a single light source at 550 nm.

Fast light-switchable polymeric carbon nitride membranes for tunable gas separation

Switchable gas separation membranes are intriguing systems for regulating the transport properties of gases. However, existing stimuli-responsive gas separation membranes suffer from either very slow response times or require high energy input for switching to occur. Accordingly, herein, we introduced light-switchable polymeric carbon nitride (pCN) gas separation membranes with fast response times prepared from melamine precursor through in-situ formation and deposition of pCN onto a porous support using chemical vapor deposition. Our systematic analysis revealed that the gas transport behavior upon light irradiation is fully governed by the polarizability of the permeating gas and its interaction with the charged pCN surface, and can be easily tuned either by controlling the power of the light and/or the duration of irradiation. We also demonstrated that gases with higher polarizabilities such as CO2 can be separated from gases with lower polarizability like H2 and He effectively with more than 22% increase in the gas/CO2 selectivity upon light irradiation. The membranes also exhibited fast response times (<1 s) and can be turned “on” and “off” using a single light source at 550 nm.

Chemical reactions of graphitic carbon nitride films with glass surfaces and their impact on photocatalytic activity

Thin films of graphitic carbon nitride (g-CN), a visible-light-driven photocatalyst, have recently attracted interest for application in photoelectrochemical cells for water splitting and high-throughput photocatalysis. In typical syntheses, g-CN films are formed by heating the nitrogen-rich precursor and substrate to 500-600 °C. The heated substrate should affect the polycondensation of the precursor and thereby alter the properties of the g-CN film. In this paper, we demonstrate that soda-lime glass, such as commercial glass slides, modifies the chemical structure of g-CN. The terminal amino groups of g-CN are partially substituted with cyanamide and hydroxyl groups. The electron-withdrawing groups provide the energy offsets of the frontier orbitals between the modified and unmodified molecules, facilitating exciton dissociation. After alkali metals are removed, the modified g-CN film exhibits a faster photodegradation of methyl orange compared with a melon film. The simple protocol to activate a g-CN film without co-catalysts paves a new way to enhance photocatalytic activity via selections of substrates, including waste glass.

Energy-Efficient CuO/TiO2@GCN Cellulose Acetate-Based Membrane for Concurrent Filtration and Photodegradation of Ketoprofen in Drinking and Groundwater

Photocatalytic membranes possessing both photocatalytic and solid-liquid separation capabilities were developed. These materials are based on ternary 1% CuO/TiO2@GCN (1:9) embedded on cellulose acetate (CA) via the phase inversion method. The CA membranes containing 0.1, 0.3 and 0.5 wt% of 1% CuO/TiO2@GCN (1:9) (CTG–100, CTG–300 and CTG–500) were fabricated. The deposition of 1% CuO/TiO2@GCN (1:9) onto the CA membranes and the consequential changes in the materials’ properties were investigated with various characterization techniques. For instance, PXRD, FTIR, and XPS analysis provided evidence that photocatalytic membranes were formed. Electron microscopy and EDX were then used to visualize the photocatalytic membranes and show that the photocatalyst (1% CuO/TiO2@GCN (1:9)) was well dispersed onto the CA membrane. On the other hand, the properties of the photocatalytic membranes were scrutinized, where it was found that the membranes had a sponge-like morphology and that was significantly less hydrophilic compared to neat CA. The removal of KP in water using CTG–500 exhibited over 94% efficiency, while 38% for neat CA was achieved. Water permeability flux improved with increasing 1% CuO/TiO2@GCN (1:9) and hydrophilicity of the membranes. The electrical energy consumption was calculated and determined to be significantly lower than that of the CA membrane. The CTG–500 membrane after every cycle showed self-cleaning ability after operation in drinking and groundwater.

Facile solvothermal assisted g-C3N4 post-grafting with aromatic amine dyes for effective photocatalytic hydrogen evolution

Dye grafted g-C3N4 using covalent bonds via a Schiff base chemical reaction exhibit much higher photocatalytic activity for H2 evolution.

In situ formation of 2-thiobarbituric acid incorporated g-C3N4 for enhanced visible-light-driven photocatalytic performance

Embedding heterocycles into the skeleton of g-C₃N₄ has been proved to be a simple and efficient strategy for improving light response and the separation of photo-excited charges. Herein, 2-thiobarbituric acid incorporated g-C₃N₄ (TBA/CN) with good photocatalytic efficiency for Rh B degradation and H₂ production was successfully achieved via a facile thermal copolymerization approach. The incorporation of aromatics and S atoms into the skeleton of g-C₃N₄ was identified via systematic characterizations. This unique structure contributed to the narrowed band-gap, extended delocalization of lone pair electrons and changed electron transition pathway, which led to the enhanced visible light utilization, accelerated charge migration and prolonged electron lifetime, subsequently resulting in the significant boost of photocatalytic activity. The optimal TBA/CN-3 sample yielded the largest Rh B degradation rate constant k value of 0.0273 min⁻¹ and simultaneously highest rate of H₂ evolution of 0.438 mmol g⁻¹ h⁻¹, which were almost 3.5 and 3.8 folds as fast as that of the pristine CN, respectively. Finally, the photocatalytic mechanism was proposed for the detailed elucidation of the process of Rh B degradation coupled with H₂ production.

Embedding heterocycles into the skeleton of g-C₃N₄ has been proved to be a simple and efficient strategy for improving light response and the separation of photo-excited charges.

A comparison study of sodium ion- and potassium ion-modified graphitic carbon nitride for photocatalytic hydrogen evolution

It is well known that modifying graphitic carbon nitride (GCN) is an imperative strategy to improve its photocatalytic activity. In this study, Na-doped and K-doped graphitic carbon nitride (GCN-Na and GCN-K) were prepared via the simple thermal polymerization of a mixture of melamine and NaCl or KCl, respectively. The structure characterization showed that both Na⁺ and K⁺ intercalation could reduce the interlayer distance of GCN and introduce cyano defects in GCN, while K⁺ apparently had a stronger influence on the structure variation of GCN. The chemical composition data showed that both Na⁺ and K⁺ could easily interact with GCN, while K-doping caused a greater change in the C/N ratio than Na-doping. Moreover, compared to GCN-Na-5 (5 represents weight ratio of alkali halide to melamine), the conduction and valence bands of GCN-K-5 both shifted upward based on the electronic and optical measurements. Consequently, GCN-K-5 yielded an H₂ evolution rate around 4 times higher than that of GCN-Na-5 under visible light irradiation (>420 nm). The cation size effect on GCN was proposed to be mainly responsible for the variation in the structure, optical and electronic properties of ion-doped GCNs, and hence the enhanced photocatalytic H₂ evolution. The current work can provide new insight into optimizing photocatalysts for enhanced photocatalytic performances.

The ion size effect on graphitic carbon nitride is responsible for variations in its structure, optical and electronic properties, and hence the enhancement in photocatalytic hydrogen evolution.

Atomic Sandwiched p-n Homojunctions

Semiconductor p-n junctions have been explored and applied in photoelectrochemical (PEC) water splitting, but serious carrier recombination and sluggish oxygen evolution reaction (OER) dynamics have demanded further progress in p-n junction photoelectrode design. Here, via a controllable NH₃ treatment, we construct sandwiched p-n homojunctions in three-unit-cells n-type SnS₂ (n-SnS₂ ) nanosheet arrays using nitrogen (N) as acceptor dopants. The optimal N-doped n-SnS₂ (pnp-SnS₂ ) with such unique structure achieves a record photocurrent density of 3.28 mA cm^-2 , which is 21 times as high as that of n-SnS₂ and the highest value among all the SnS₂ photoanodes reported so far. Moreover, the stoichiometric O₂ and H₂ evolution from water was achieved with Faradaic efficiencies close to 100 %. The superior performance could be attributed to the facilitated electron-hole separation/transfer, accelerated surface OER kinetics, prolonged carrier lifetime, and improved structural stability.

Molecular Mechanism for the Self-Supported Synthesis of Graphitic Carbon Nitride from Urea Pyrolysis

Quantum chemical calculations combined with kinetic Monte Carlo simulations are performed to decipher the kinetics for the one-pot synthesis of two-dimensional graphitic carbon nitride (g-C₃N₄) from urea pyrolysis. Two mechanisms are considered, one involving ammelide as the intermediate compound and the other considering cyanuric acid. Different grid growing patterns are investigated, and the size, shape, and density of the grids as well as the number and position of the defects are evaluated. We find that the mechanistic pathway involving ammelide is preferred. Larger g-C₃N₄ grids with lower density are achieved when the rate constant for melon growing is inversely proportional to the number of local reaction sites, while nearly filled smaller grids are obtained in the opposite scenario. Larger defects appear at the grid periphery while smaller holes appear throughout the grid. The synthesis of extended g-C₃N₄ structures is favored if the g-C₃N₄ growing propensity is directly proportional to the number of reaction sites.

Eosin-Y and sulfur-codoped g-C3N4 composite for photocatalytic applications: the regeneration of NADH/NADPH and the oxidation of sulfide to sulfoxide

The successful development of eosin-Y and sulfur-codoped g-C3N4 composite as a highly efficient photocatalyst for the regeneration of NADH/NADPH (64.38%/81.14%) and the light-driven oxidation of sulfide to sulfoxide with an yield of 99.6%.

Arylamine organic dye-functionalized g-C3N4 formed through cycloaddition reactions and its application in photocatalytic hydrogen evolution

The arylamine organic dye grafted g-C3N4 by covalent azomethine ylide bonds via 1,3-dipolar cycloaddition is successfully prepared, which is the as-obtained g-C3N4/TPA-CNCHO photocatalyst with much enhanced photocatalytic activity for H2 production.

Z-Scheme LaCoO3/g-C3N4 for Efficient Full-Spectrum Light-Simulated Solar Photocatalytic Hydrogen Generation

Photocatalytic decomposition of water is the most attractive method for the sustainable production of hydrogen, but the development of a highly active and low-cost catalyst remains a major challenge. Here, we report the preparation of LaCoO3/g-C3N4 nanosheets and the utilization of LaCoO3 instead of noble metals to improve the photocatalytic activity for the production of hydrogen. First, LaCoO3 was successfully prepared by the sol-gel method, and then a series of highly efficient Z-scheme LaCoO3/g-C3N4 heterojunction photocatalysts were synthesized by the solvothermal method. Various characterization techniques (X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (DRS), photoluminescence (PL), transient photocurrent response test, electron paramagnetic resonance (EPR)) confirm that the heterostructure and interfacial interaction had been formed between LaCoO3 nanoparticles and g-C3N4 nanosheets. In the photocatalytic water splitting test, LaCoO3/g-C3N4-20 wt % exhibited the highest photocatalytic activity of 1046.15 μmol h-1 g-1, which is 3.5 and 1.4 times higher than those of LaCoO3 and g-C3N4, respectively. This work leads to an inexpensive and efficient LaCoO3/g-C3N4 photocatalysis system for water splitting or other photocatalytic applications.

Emerging Chemical Functionalization of g-C3N4: Covalent/Noncovalent Modifications and Applications

Atomically 2D thin-layered structures, such as graphene nanosheets, graphitic carbon nitride nanosheets (g-C₃N₄), hexagonal boron nitride, and transition metal dichalcogenides are emerging as fascinating materials for a good array of domains owing to their rare physicochemical characteristics. In particular, graphitic carbon nitride has turned into a hot subject in the scientific community due to numerous qualities such as simple preparation, electrochemical properties, high adsorption capacity, good photochemical properties, thermal stability, and acid-alkali chemical resistance, etc. Basically, g-C₃N₄ is considered as a polymeric material consisting of N and C atoms forming a tri-s-triazine network connected by planar amino groups. In comparison with most C-based materials, g-C₃N₄ possesses electron-rich characteristics, basic moieties, and hydrogen-bonding groups owing to the presence of hydrogen and nitrogen atoms; therefore, it is taken into account as an interesting nominee to further complement carbon in applications of functional materials. Nevertheless, g-C₃N₄ has some intrinsic limitations and drawbacks mainly related to a relatively poor specific surface area, rapid charge recombination, a limited light absorption range, and a poor dispersibility in both aqueous and organic mediums. To overcome these shortcomings, numerous chemical modification approaches have been conducted with the aim of expanding the range of application of g-C₃N₄ and enhancing its properties. In the current review, the comprehensive survey is conducted on g-C₃N₄ chemical functionalization strategies including covalent and noncovalent approaches. Covalent approaches consist of establishing covalent linkage between the g-C₃N₄ structure and the chemical modifier such as oxidation/carboxylation, amidation, polymer grafting, etc., whereas the noncovalent approaches mainly consist of physical bonding and intermolecular interaction such as van der Waals interactions, electrostatic interactions, π-π interactions, and so on. Furthermore, the preparation, characterization, and diverse applications of functionalized g-C₃N₄ in various domains are described and recapped. We believe that this work will inspire scientists and readers to conduct research with the aim of exploring other functionalization strategies for this material in numerous applications.

Polymer Brushes on Graphitic Carbon Nitride for Patterning and as a SERS Active Sensing Layer via Incorporated Nanoparticles

Graphitic carbon nitride (gCN) has a broad range of promising applications, from energy harvesting and storage to sensing. However, most of the applications are still restricted due to gCN poor dispersibility and limited functional groups. Herein, a direct photografting of gCN using various polymer brushes with tailorable functionalities via UV photopolymerization at ambient conditions is demonstrated. The systematic study of polymer brush-functionalized gCN reveals that the polymerization did not alter the inherent structure of gCN. Compared to the pristine gCN, the gCN-polymer composites show good dispersibility in various solvents such as water, ethanol, and tetrahydrofuran (THF). Patterned polymer brushes on gCN can be realized by employing photomask and microcontact printing technology. The polymer brushes with incorporated silver nanoparticles (AgNPs) on gCN can act as a multifunctional recyclable active sensing layer for surface-enhanced Raman spectroscopy (SERS) detection and photocatalysis. This multifunctionality is shown in consecutive cycles of SERS and photocatalytic degradation processes that can be applied to in situ monitor pollutants, such as dyes or pharmaceutical waste, with high chemical sensitivity as well as to water remediation. This dual functionality provides a significant advantage to our AgNPs/polymer-gCN with regard to state-of-the-art systems reported so far that only allow SERS pollutant detection but not their decomposition. These results may provide a new methodology for the covalent functionalization of gCN and may enable new applications in the field of catalysis, biosensors, and, most interestingly, environmental remediation.