Metal-free Materials Research Articles

Advanced Analytical Electron Microscopy Techniques for Probing Individual PGM-Free Catalyst Sites

Hydrogen fuel cells currently utilize expensive platinum group metal nanoparticles as catalysts [1]. To reduce the cost of catalyst materials, large efforts to develop viable platinum group metal-free (PGM-free) catalyst materials, which often consist of single transition metal atoms embedded in nitrogen-doped graphitic carbon structures, are being undertaken [2]. Given the atomic-scale nature of the metal sites in these materials, their performance and stability are highly dependent on the local coordination environment and consequently electronic structure of the sites [3]. A detailed understanding of the local elemental composition and lattice structure of individual sites, and how these properties vary between sites, is therefore needed to further develop improved PGM-free catalyst materials. While many bulk techniques are available that can provide average properties of these sites, such as Mössbauer and X-ray absorption spectroscopies, techniques with high spatial resolution are needed to measure the properties of individual sites. As a result, scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS) has proven an invaluable tool for characterization of these materials due to its ability to probe structural and electronic properties at the atomic scale [4]. However, combined with the instability of many metal sites under the electron probe, the quantity and type of information accessible by conventional STEM instrumentation and acquisition methods is limited. To better understand the local coordination environment and electronic structure of individual sites, as well as how these properties vary site to site, new techniques and hardware are therefore needed.Here, we demonstrate advancements in STEM-EELS and -EDS that allow the quality and quantity of spectroscopic information obtained from individual sites to be significantly improved over conventional method. First, we demonstrate direct real-space mapping of metal sites by using a direct electron detector in the EELS spectrometer. This increases the data acquisition rate and signal-to-noise ratio sufficiently to map metal atom positions at the atomic scale. In addition, we show how automated metal atom position identification and subsequent probe positioning allow the rate at which metal sites are probed to be increased by another order of magnitude while simultaneously increasing the quantity of data obtained from each site. Using EELS and EDS signals acquired in parallel, this automated acquisition method enables a wide range of metal site elements to be identified, as well as the local coordination environment around the sites to be determined. Combined with electronic structure measurements of the metal atoms themselves, this technique provides significantly more information about individual sites than conventional methods. The techniques presented here are therefore poised to significantly improve our understanding of the local coordination environment and electronic structure of individual PGM-free metal sites, as well how these properties vary site to site, accelerating development of these low-cost hydrogen fuel cell catalyst materials [5].

Zinc Anodes with Electrodeposited Ionomer Protection Layer for Rechargeable Zinc-Air Batteries

Metal air batteries are assembled from a metal anode and a porous cathode in a suitable electrolyte. They combine the design of fuel cells and conventional batteries and have been demonstrated to have large theoretical energy densities higher compared to devices based on Li-ion chemistry, due to the ability to use air at the cathode and to exchange two electrons per zinc atom. ZAB represent a safe, environmentally benign, affordable and simple way to store and deliver electrical energy for a wide variety of devices. However, research efforts are necessary to increase the efficiency of rechargeable ZAB and mitigate obnoxious occurrences that decrease the number of charge-discharge cycles such as zinc dendrite formation, cathode degradation and alkaline electrolyte carbonation.The protection of zinc metal anodes in zinc-air batteries (ZAB) is an efficient way to reduce corrosion and Zn dendrite formation and improve cyclability and overall battery efficiency. The extent of improvement depends on the type and thickness of the protective layer.In this work, we explore an advanced coating of the zinc anode by anion-conducting poly(N-vinylbenzyl, N,N,N trimethylammonium) chloride (PVBTMA) that is electropolymerized directly on the zinc metal. The Zn deposition in presence of quaternary ammonium salts and polyelectrolytes was recently studied to improve the cyclability. The major advances foreseen by this approach are excellent qualities of the metal/ionomer interface, due to the in-situ deposition process, improving the corrosion protection and the selective anion permeability; furthermore, the chosen ionomer presents a high stiffness and strength to resist the formation of zinc dendrites, due to the stiff polystyrene backbone. Moreover, the presence of a polyelectrolyte separator facilitates device miniaturization. The zinc anode protection layer was observed by optical microscopy and scanning electron microscopy (Figure : SEM micrographs of Zn pellet with PVBTMA layer: a) from 0.01 M precursor solution, b) and c) from 0.1 M precursor solution) .and the wettability of the ionomer-coated zinc surface was investigated by contact angle measurements.The resulting ZAB battery with PVBTMA anode coating is analyzed in terms of cyclability in alkaline electrolyte and solid-state configuration using a Whatman paper separator.The goal is to pair metal-free electrode materials with appreciable catalytic activity for oxygen reduction and evolution with a zinc anode that has a protection layer against dendrite formation to maximize efficiency. Figure 1

Oxygen-assisted one-step fabrication and concomitant regulation of hierarchical carbon nanosheet assemblies with conjugated binding configurations for promoted H2O2 electrosynthesis

Electrochemical two-electron oxygen reduction reaction (2e- ORR) is a straightforward and efficient route for H2O2 production. The facile fabrication and concomitant modulation of metal-free carbon with conjugated binding configurations is currently an essential obstacle for 2e− ORR toward electrochemical H2O2 generation. Herein, hierarchical porous O, N co-doped porous carbon (ONPC) nanosheet assemblies with multiple active motifs are developed for driving H2O2 electrogeneration from 2e- ORR. The pyrrolic-N and C = O configurations in ONPC facilitate the highly selective electrosynthesis of H2O2. The synthesis and concomitant regulation of pyrrolic-N and C = O of carbon materials are achieved via a simple one-step oxygen-assisted self-activation, self-template and self-doping strategy. The resulted amorphous ONPC-700 with the optimal pyrrolic − N and C = O active motifs facilitates the 2e− ORR toward H2O2 electrosynthesis. A high H2O2 yield of 0.319 mol g−1 h−1 with 80–93% H2O2 selectivity, good methanol tolerance, and long-term stability in 0.1 M KOH can be achieved. This study inspires to develop and regulate metal-free carbon materials with dual active motifs via one-step oxygen-mediated pyrolysis of low-cost/non-toxic precursor for H2O2 electrosynthesis.

Synthesis of metal-free nitrogen-doped mesoporous carbon nanosheets with reference to molecular self-assembly for efficient peroxymonosulfate activation

The application of metal-free carbon materials in Sulfate radical-based advanced oxidation processes (SR-AOPs) has attracted great attention. In SR-AOPs, porosity and active sites are the keys for nitrogen-doped carbon materials to exhibit high catalytic activity. In this paper, melamine and gallic acid were selected as raw materials, preparing metal-free nitrogen-doped carbon materials by using the molecular self-assembly synthesis method. The catalysts with different structural morphology and surface chemistry were obtained by controlling the pyrolysis temperature. It proposed the formation mechanism of nitrogen-doped mesoporous carbon nanosheets (NMC). The pyrolysis temperature was critical for the regulation of surface properties as well as the structure of carbon materials. It was found that NMC-800 exhibited fluffy and porous microstructure, and various active sites on the surface of the catalyst, including graphite N, pyridine N and CO. In the NMC-800/PMS system, the SMX degradation efficiency and corresponding rate constant could achieve 90.3 % and 0.1705 min−1, respectively. Besides, the degradation pathways and intermediate products of SMX were discussed by the analysis of quenching experiments, electron spin resonance (ESR) and liquid chromatography-mass spectrometry (LC-MS).

Jasmine waste derived biochar as green sulfate catalysts dominate non-free radical paths efficiently degraded tetracycline

Because of the potential environmental harm caused by the extensive application of tetracycline (TC), this study used jasmine waste rich in organic matter as a precursor and one-step carbonization into metal-free carbon-based materials to efficiently activate peroxymonosulfate (PMS) toward degrading TC. The jasmine waste biochar (JWB) with a heating rate of 10 °C min−1 and a heating temperature of 700 °C was selected as the most suitable material based on its catalytic performance. The effects of catalyst dose, PMS dose, initial pH value, coexisting inorganic anions and TC concentration on the JWB/PMS/TC system were thoroughly optimized. The results showed that the degradation efficiency of TC by JWB/PMS system was 90%. Meanwhile, the combination of electron paramagnetic resonance, masking experiments and X-ray photoelectron spectrometry confirmed that JWB degraded TC mainly through the non-radical radical pathway of 1O2 oxidation and mediated the electron transfer to PMS. In addition, some degradation products were analyzed by LC-MS and possible degradation pathways of the system were proposed. Therefore, this paper proposes a novel method for recycling jasmine waste and providing a low-cost catalyst for the oxidation treatment of refractory organic matter.

Fluorine and oxygen-functionalized silicon nitride with abundant oxygen vacancies for cataluminescence sensing of H2S

Efficient, selective and highly sensitive detection of H2S is important for environmental protection and human security. Nanomaterials-based cataluminescence (CTL) sensors, especially metal-free catalysts, have been used for gas sensing. Herein, due to the efficient electron transfer and high specific area of silicon nitride (Si3N4), combined with the strong electronegativity of fluorine and oxygen, we purposely synthesized F and O-modified Si3N4 (F/O-Si3N4) by engineering surface states and catalytic properties. We then used it to construct a H2S CTL gas sensor. Compared with other metal-based CTL sensors, the F/O-Si3N4-based CTL system exhibited high sensitivity and a longer lifetime stability. The detection limit was 0.027 μg mL−1 in the detection range of 0.49–8.17 μg mL−1, and a relative standard deviation (RSD) of better than 3.3% were obtained. Further research demonstrated the luminescence mechanism, in which the rich oxygen vacancies of Si3N4 promoted the adsorption of O2 and the formation of F-Si sites due to the catalytic oxidation of H2S and the generation of SO2*. This served as the main emitter accounting for the strong CTL emission. This work is the first report of the application of Si3N4 as a catalyst for CTL H2S sensing. This will expand the methods for enhancing the catalytic activity and practical applications of metal-free materials.

Waste leather derived porous carbon boosted Fenton oxidation towards removal of diethyl phthalate: Mechanism and long-lasting performance

The acceleration of Fe(III)/Fe(II) conversion in Fenton systems is the critical route to achieve the long-lasting generation of reactive oxygen species towards the oxidation of refractory contaminants. Here, we found that waste leather derived porous carbon materials (LPC), as a simple and readily available metal-free biochar material, can promote the Fe(III)/H2O2 system to generate hydroxyl radicals (•OH) for oxidizing a broad spectrum of contaminants. Results of characterizations, theoretical calculations, and electrochemical tests show that the surface carbonyl groups of LPC can provide electron for direct Fe(III) reduction. More importantly, the graphitic-N on surface of LPC can enhance the reactivity of Fe(III) for accelerating H2O2 induced Fe(III) reduction. The presence of LPC accelerates the Fe(III)/Fe(II) redox cycle in the Fe(III)/H2O2 system, sustainable Fenton chain reactions is thus initiated for long-lasting generation of hydroxyl radicals without adding Fe(II). The continuous flow mode that couples in-situ Fenton-like oxidation and LPC with excellent adsorption catalytic properties, anti-coexisting substances interference and reusability performance enables efficient, green and sustainable degradation of trace organic pollutants. Therefore, the application of metal-free carbon materials in Fenton-like system can solve its rate-limiting problem, reduce the production of iron sludge, achieve green Fenton chemistry, and facilitate the actual engineering application of economic and ecological methods to efficiently remove trace organic contaminants from actual water sources.

Fluorine and nitrogen dual-doped carbon material as metal-free peroxymonosulfate activator for efficient tetracycline degradation: Radical-free mechanism

Persulfate-based advanced oxidation technology holds great potential for antibiotic treatment. However, its low activity, metal ion leaching, and poor stability mainly limit the practical application. Fluorine-nitrogen heteroatomic dual-doping carbon material (F, N-CM) was successfully prepared using ZIF-8 metal–organic frameworks as a precursor. F, N-CM exhibited high peroxymonosulfate (PMS) activation capability for tetracycline (TC) degradation. The incorporation of F and N dopants in F, N-CM created abundant defects and active sites, facilitating the activation of PMS. Notably, the presence of fluorine atomic lone electron pairs significantly enhanced electron transfer from PMS to TC. The high degradation performance of the F, N-CM/PMS system was primarily attributed to radical-free pathways involving singlet oxygen and electron transfer. Furthermore, F, N-CM demonstrated good stability for PMS activation and could be regenerated through simple calcination. This research provides a novel strategy for developing metal-free carbon materials with dual-doped heteroatoms as effective catalyst for PMS activation and degradation of refractory organic pollutants.

3D structured photocatalysts for sustainable H2O2 generation from saccharides derivatives

The possibility of using hydrogen peroxide (H2O2) as a chemical oxidizer or as a green liquid fuel to produce electricity has encouraged both the scientific and industrial communities to investigate green technologies aimed at the sustainability of the production process. In particular, the light-induced synthesis of H2O2 from water and oxygen has attracted significant attention using optical semiconductors.An exfoliated metal-free graphitic carbon nitride material (GCN-T) was prepared and tested for the photocatalytic production of H2O2 using five saccharides (arabinose, cellobiose, fructose, glucose, and sorbitol) as sacrificial electron donors. The results showed that the scavenging efficiency of the photogenerated holes rapidly increases with the number of –OH groups in the molecular structure of these sacrificial agents. Among the polyhydroxy compounds tested, the highest concentration of H2O2 was achieved using cellobiose.To develop a technological approach for H2O2 production, the GCN-T photocatalyst was immobilized on a 3D printed structure (GCN-T/3D structure), which showed high stability with both ultrapure water and seawater after several reusability runs. This innovative photocatalytic structure enables remarkable efficiency for H2O2 production, with an apparent quantum efficiency (AQE) of 17% at 412 nm radiation, compared to 12% obtained with GCN-T in suspension.

Unravelling the role of boron dopant in borocarbonitirde catalytic dehydrogenation reaction

Borocarbonitride (BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation (ODH) of alkanes. However, the in-depth understandings on the role of boron (B) dopants and the intrinsic activities of –C=O and –B–OH still remain unknown. Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion (∼57%) and styrene selectivity (∼83%) are achieved in ODH for B1CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B5CN. Structural characterizations and kinetic measurements indicate that –C=O and –B–OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of –C=O (5.556 × 10−4 s−1) is found to be 23.7 times higher than –B–OH (0.234 × 10−4 s−1) site. More importantly, we reveal that the deep oxidation to undesirable CO2 occurs on –C=O rather than –B–OH site, and B dopant in BCN materials can reduce the nucleophilicity of –C=O site to eliminate the CO2 emission. Overall, the present work provides a new insight on the structure–function relationship of the BCN catalytic systems.

Nonconjugated Redox-Active Polymers: Electron Transfer Mechanisms, Energy Storage, and Chemical Versatility.

The storage of electric energy in a safe and environmentally friendly way is of ever-growing importance for a modern, technology-based society. With future pressures predicted for batteries that contain strategic metals, there is increasing interest in metal-free electrode materials. Among candidate materials, nonconjugated redox-active polymers (NC-RAPs) have advantages in terms of cost-effectiveness, good processability, unique electrochemical properties, and precise tuning for different battery chemistries. Here, we review the current state of the art regarding the mechanisms of redox kinetics, molecular design, synthesis, and application of NC-RAPs in electrochemical energy storage and conversion. Different redox chemistries are compared, including polyquinones, polyimides, polyketones, sulfur-containing polymers, radical-containing polymers, polyphenylamines, polyphenazines, polyphenothiazines, polyphenoxazines, and polyviologens. We close with cell design principles considering electrolyte optimization and cell configuration. Finally, we point to fundamental and applied areas of future promise for designer NC-RAPs.

Tubular C3N4 Nanotubes as Metal-Free Sulfur Hosts toward Stable Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) with high energy density have the potential to replace current commercial lithium-ion batteries. However, the shuttle effect and the low conversion kinetics of lithium polysulfide (LiPS) remain the main challenges in the development of LSBs. In this study, a metal-free and simple-to-prepare carbon nitride with a high surface area and tubular morphology (CN-nt) is used as the sulfur host for LSBs. Due to its unique nanostructure and rich active sites, it not only effectively disperses the active sulfur material and anchors soluble polysulfide species, but it also promotes the nucleation process of Li2S, thus achieving fast and sustainable Li-S redox reactions. Experimental results show that the obtained S@CN-nt electrodes exhibit a high sulfur utilization of 1296.2 mAh g−1 at 0.1 C and a significant rate capability of 689.4 mAh g−1 at the high current rate of 3C. More importantly, the capacity retention reaches 87.7% after 500 cycles. This simple strategy of engineering unique carbon-based nanostructured hosts can inspire new ideas for developing cost-effective and metal-free host materials for sulfur-based batteries.

The performance of heteroatom-doped carbon nanotubes synthesized via a hydrothermal method on the oxygen reduction reaction and specific capacitance

Due to the increasing demand for electrochemical energy storage, various novel electrode and catalysis materials for supercapacitors and rechargeable batteries have developed over the last decade. The structure and characteristics of these catalyst materials have a major effect on the device's performance. In order to lower the costs associated with electrochemical systems, electrochemical systems, metal-free catalysis materials can be employed. In this study, metal-free catalysts composed of nitrogen (N) and sulfur (S) dual-doped multi-walled carbon nanotubes were synthesized using a straightforward and cost-effective single-step hydrothermal method. Carbon nanotubes served as the carbon source, while l-cysteine amino acid and thiourea acted as doping elements. As a result of the physicochemical characterization, many defects and a porous structure were noted, along with the successful insertion of nitrogen and sulfur into the carbon nanotube was confirmed. According to the cyclic voltammetry tests for the dual-doped samples in alkaline conditions, the D-CNT2 catalyst exhibited onset potentials of -0.30 V higher than the -0.37 V observed for the D-CNT3 catalyst. This indicates enhanced oxygen–reduction reaction due to the synergistic effects of the heteroatoms in the structure and the presence of chemically active sites. Moreover, the outstanding specific capacitance of the D-CNT2 catalyst (214.12 F g-1 at scanning rates of 1 mV s-1) reflects the effective porosity of the proposed catalyst. These findings highlight the potential of N/S dual–doped carbon nanotubes for electrocatalytic applications, contributing to efficient energy conversion.

A Pentagonal Defect-Rich Metal-Free Carbon Electrocatalyst for Boosting Acidic O2 Reduction to H2O2 Production

Metal-free carbon-based materials are considered one of the most promising two-electron oxygen reduction reaction (2e- ORR) electrocatalysts for the green synthesis of hydrogen peroxide (H2O2). However, most reported carbon electrocatalysts perform much more effectively in alkalis than in acids. Herein, by creatively using fullerene (C60) as the precursor subject to ammonia treatment, we designed and synthesized a pentagonal defect-rich nitrogen-doped carbon nanomaterial (PD/N-C). It achieves outstanding ORR activity, 2e- selectivity, and stability in acidic electrolytes, surpassing the benchmark PtHg4 alloy catalyst. Impressively, the flow cell based on the PD/N-C catalyst achieves nearly 100% Faraday efficiency with a remarkable H2O2 yield, representing the best improvement among all the metal-free catalysts. Experimental and theoretical results reveal that such superb 2e- ORR performance of PD/N-C originates from the synergism between pentagonal defects and nitrogen dopants. This work presents an effective strategy for the design and construction of highly efficient acid-resistant carbon electrocatalysts for H2O2 production and beyond.

Direct Anodic Conversion of 4-Hydroxybenzaldehydes into Benzoquinones

A novel electrosynthetic protocol for the direct conversion of easily accessible 4-hydroxybenzaldehydes into valuable benzoquinones is reported. The transformation is enabled through anodic oxidation and is performed in a reagent-free manner devoid of terminal oxidants and redox mediators to effectively minimize waste. Environmentally benign and inexpensive graphite serves as a metal-free anode material. A broad range of substituents, including halogens, are tolerated in this electrochemical protocol, and the quinones are selectively accessible in yields up to 99%. Furthermore, the compatibility with electrochemical flow synthesis is demonstrated. Moreover, the flow protocol is successfully applied to the biopolymer lignosulfonate and provides quinones in yields up to 7.6 wt%. A mechanistic proposal for this Dakin-type reaction is offered. The sustainability and synthetic utility are evaluated quantitatively and compared to established protocols by application of different green chemistry metrics.

Ni–CoS2/WS2/MoS2 hollow cuboids as noble metal-free bifunctional catalysts for highly efficient photovoltaics and electrochemical hydrogen production

Transition metal compounds, especially NiS2, CoS2, WS2, and MoS2 as noble metal-free catalyst materials, are widely applied to replace Pt in the fields of dye-sensitized solar cells (DSSCs) and hydrogen evolution reactions (HER). Meanwhile, hollow structures have large specific surface area and their large void spaces can also effectively reduce ion migration resistance and diffusion length. In this work, Ni–CoS2/WS2 and Ni–CoS2/MoS2 hollow cuboids have been successfully synthesized and applied as promising bifunctional electrocatalysts in high-efficiency DSSCs and HERs. In detail, nickel-cobalt hydroxide cuboids were prepared and served as self-sacrificing templates to react with (NH4)2WS4 or (NH4)2MoS4 at room temperature, and then mixed with sulfur powder for annealing treatment. Besides, Ni–CoS2 hollow cuboids were synthesized as a reference. Profiting from the stable hollow structure, large specific surface area, abundant effective active sites exposed by WS2, and synergistic effect of multiple elements, Ni–CoS2/WS2 hollow cuboids manifested a preeminent performance. Compared with Pt (8.06%), the conversion efficiency of Ni–CoS2/WS2 hollow cuboids had reached 9.41% as counter electrode for DSSCs. As for HER, it exhibited the lowest overpotential of 72.4 mV@10 mA cm−2 and had the minimum Tafel slope (56.1 mV dec−1) compared with Ni–CoS2/MoS2 and Ni–CoS2.

Green Room-Temperature Phosphorescent Carbon Dots with a Lifetime of around 1 s

Organic ultralong room-temperature phosphorescence (RTP) has attracted extensive attention and has been a sparklingly heated topic due to its promising applications in bioimaging, encryption, and optoelectronic devices. However, the synthesis procedures for these materials are always cumbersome, costly, and involve toxic substances as well. Herein, a facile, low-cost, and hypotoxic strategy has been developed to achieve green RTP by the hydrothermal reaction of carbon source together with boric acid, resulting in the in situ rigidification of carbon dots into the B2O3 matrix. The designed green RTP carbon dots (CDs@B2O3) exhibited an ultralong lifetime of 905.5 ms, lasting more than 8 s. This excellent performance was mainly due to the restricted vibration and rotation of CDs by the covalent bond formation and the suppressed nonradiative recombination of triplet excitons via B2O3 matrix rigidification. Moreover, we demonstrated the practical applications of the prepared CDs for bioimaging, anti-counterfeiting, and information encryption. This work provides design principles to construct metal-free RTP materials with ultralong lifetime and high stability for promising remarkable applications.

Bright green phosphorescent carbon dots prepared from natural vitamins for information encryption

Materials with room temperature phosphorescence (RTP) have long lifetimes and large Stokes shifts, making them excellent candidates for bioimaging, anticounterfeiting, and encryption applications. As a metal-free RTP material, carbon dots (CDs), have received considerable attention. Using vitamin B9 (V) and ethylenediamine (EDA) as raw materials, blue fluorescent VCDs are synthesized by a one-step hydrothermal process in our study. A boric acid (BA) matrix is then used to embed the CDs, and VCDs@BA is prepared as an environmentally friendly and economical RTP material. Bright blue fluorescence and vivid green phosphorescence are released by VCDs@BA. The phosphorescence may last up to 6.0 s and has a lifespan of 311 ms. The photoluminescence quantum yield of the material is as high as 11.03%. VCDs@BA has been utilized effectively in applications for information security and anti-counterfeiting because of its optic property. This research offers a sustainable method for the synthesis of RTP materials, which is a feasible way to create room-temperature phosphorescent materials with excellent efficacy and prolonged afterglow durations.

Two-Dimensional Silver-Metalated Graphdiyne Nanosheets for Photocatalytic Degradation of Antibiotics

The two-dimensional layered carbon allotrope graphdiyne (GDY) is formed by combining hybridized sp–sp2 carbon atoms. This alkynyl-bonded 2D carbon network with tunable energy levels and high carrier-mobility has excellent potential in solar energy utilization. However, the standard but complex synthesis method of GDYs by epitaxial growth on a metal-crystal surface and the poor activity of metal-free materials limit applications beyond the lab. Here, we produce a silver-metalated GDY (Ag-GDY) through a facile and scalable wet-chemistry strategy, featured by an appropriate band gap at 2.61 eV and good e–/h+ separation ability. These unique characteristics facilitate the reaction between Ag-GDY and oxygen to form a variety of active free radicals. The Ag-GDY photocatalyst displays an excellent ability for the light-driven decomposition of antibiotics. Tetracycline with a concentration as low as 5.0 × 10–5 M is degraded within 30 min by Ag-GDY, showing excellent performance stability of up to five reuse cycles.

Strong ferromagnetism of g-C3N4 achieved by atomic manipulation

Two-dimensional (2D) metal-free ferromagnetic materials are ideal candidates to fabricate next-generation memory and logic devices, but optimization of their ferromagnetism at atomic-scale remains challenging. Theoretically, optimization of ferromagnetism could be achieved by inducing long-range magnetic sequence, which requires short-range exchange interactions. In this work, we propose a strategy to enhance the ferromagnetism of 2D graphite carbon nitride (g-C3N4), which is facilitating the short-range exchange interaction by introducing in-planar boron bridges. As expected, the ferromagnetism of g-C3N4 was significantly enhanced after the introduction of boron bridges, consistent with theoretical calculations. Overall, boosting ferromagnetism of 2D materials by introducing bridging groups is emphasized, which could be applied to manipulate the magnetism of other materials.