N,S,O triply-doped carbon with nanotubes-interwoven nanosheets encapsulated Co nanoparticles for robust antibiotic destruction via activating peroxymonosulfate.

The development of facile and effective approaches to regulate the stability and reusability of metallic Co catalytic materials towards peroxymonosulfate (PMS) activation for remediating antibiotic pollutants remains challenging. In this study, we develop a one-step pyrolysis strategy to fabricate three-dimensional porous architecture assembled with N,S,O-codoped carbon nanotube-interwoven hierarchically porous carbon nanosheets encapsulated Co nanoparticles (Co@NSOC), which serve as chainmail catalysts for stable and reusable degradation of tetracycline hydrochloride (TCH) through PMS activation. The optimal Co@NSOC-700-activated PMS system presents an excellent removal efficiency of 94.1 % for TCH within 10 min and a high cycling efficiency of 92.9 % after eight cycles. The encapsulated structure, abundant catalytic sites, superior hydrophilicity and strong magnetism contribute to the high performance. Further investigation demonstrates that both radical and nonradical pathways contribute to the TCH destruction, and 1O2 is verified as the dominant reactive substance. The possible degradation pathways and the toxicity of intermediates for TCH are evaluated. This work offers an innovative structure design and surface modulation strategy to fabricate robust catalysts towards environmental remediation.

Architecture engineering of Fe/Fe2O3@MoS2 enables highly efficient tetracycline remediation via peroxymonosulfate activation: Critical roles of adsorption capacity and redox cycle regulation.

Design and synthesis of high-efficiency multicomponent nanostructure for activating peroxymonosulfate (PMS) to destruct emerging antibiotics remains a daunting challenge. We report herein the simplest one-step hydrothermal construction of hierarchical Fe/Fe2O3@MoS2 architecture composed of MoS2 nanosheets integrated commercial Fe2O3 nanoparticles. The fabricated Fe/Fe2O3@MoS2 architecture can be utilized as an efficient PMS activator to destruct tetracycline hydrochloride (TCH) with a removal efficiency of 90.3 % within 40 min, outperforming Fe2O3 nanoparticles, MoS2 nanosheets analogues and many MoS2-based materials. The Fe/Fe2O3@MoS2/PMS works well under various reaction conditions, and SO4•- and 1O2 are identified as major reactive oxygen species. Thirteen intermediates towards TCH destruction are detected via four pathways, and their acute/chronic toxicity and phytotoxicity are assessed. The origins of Fe/Fe2O3@MoS2/PMS system for efficient degrading TCH are ascribed to the synergy catalysis between Fe2O3 and MoS2, which originate from: (a) the exposed Mo4+ sites on catalyst surface facilitating high-speed electron transfer from MoS2 to Fe3+ and accelerating the Fe2+ regeneration; (b) the generated Fe0 serving as an excellent electron donor to jointly promote Fe3+/Fe2+ redox cycle. This study provides a simple way to establish architecture for synergistically promoting PMS-mediated degradation.

Synergetic enhancement of electrochemical H2O2 detection in a nitrogen-doped carbon encapsulated FeCo alloy architecture.

The development of Earth-abundant metal-based non-enzymatic electrodes with ultralow metal loadings for the efficient detection of hydrogen peroxide (H2O2) is highly desirable. We report here a remarkable three-dimensional nitrogen-doped porous carbon (NPC) encapsulated Earth-abundant metal architecture, i.e., NPC encapsulating FeCo alloy nanoparticles toward highly efficient electrochemical H2O2 detection. Specifically, an Fe0.06Co0.04@NPC-950 modified electrode can show excellent electrochemical performance for non-enzymatic H2O2 sensing in neutral media, with a wide linear range of 0.004 to 8 mM, a high sensitivity of 794 µA mA-1 cm-2 and a low limit of detection (LOD) of 0.13 µM, outperforming most of the reported non-noble metal electrocatalysts. Meanwhile, the fabricated Fe0.06Co0.04@NPC-950 modified electrode is capable of real-time monitoring of H2O2 in commercial orange juice, milk and serum, revealing its application potential toward the accurate detection of H2O2 in real-sample analysis. This electrode also has high selectivity, long-term stability and good reproducibility. Its excellent performance is correlated with the synergetic catalysis of the FeCo alloy, nitrogen-rich NPC with a large specific surface area (SSA) and the core-shell structure protecting the active sites from corrosion. This study offers an efficient pathway for developing high-performance and Earth-abundant catalysts toward electrochemical H2O2 detection.

Room-Temperature Sustainable Synthesis of Selected Platinum Group Metal (PGM = Ir, Rh, and Ru) Nanocatalysts Well-Dispersed on Porous Carbon for Efficient Hydrogen Evolution and Oxidation.

Electroless deposition via a spontaneous redox reaction between the metal precursor and support is believed to be a promising approach for the syntheses of supported metal nanoparticles (SMNPs). However, its widespread applications are significantly prohibited by the low reductivity and high cost of support. To overcome these shortcomings, a porous carbon (PC) is herein developed as a promising matrix for the electroless deposition of metal NPs. Benefiting from abundant oxygen-based surface functional groups, the PC shows stronger reducibility (low redox potential) than conventional carbon substrate such as carbon nanotubes or graphene oxide, enabling a facile electroless deposition of Ir, Rh, and Ru NPs on its surface. These SMNPs exhibit an impressive electrocatalytic activity for the hydrogen evolution reaction (HER) or hydrogen oxidation reaction (HOR). For example, the Rh NP/PC can deliver an HER current density of 10 mA cm-2 with a small overpotential of 21 mV in 0.5 m H2 SO4 , while the Ru NP/PC exhibits excellent HOR activity in 0.1 m KOH in terms of high mass and surface specific exchange current density of 263 A g-1 Ru and 0.227 mA cm-2 Ru . The present strategy may open up opportunities for mass production of efficient supported NPs for diverse applications.

Electrochemical performance of ruthenium nanoparticles decorated on nitride carbon for non-enzymatic detection of hydrogen peroxide.

Development of high-performance Pt-free non-enzymatic hydrogen peroxide (H2O2) sensors on the basis of supported metal nanoparticles (NPs) is important for industrial and biological applications. Here, we report the preparation of ultrafine, surface-clean, and well-distributed Ru NPs and concomitant formation of nitride carbon (Ru/NC) by pyrolyzing tris(2,2'-bipyridyl)ruthenium(ii) chloride (TBRC) with carbon. The use of the nitrogen (N)-containing Ru complex of TBRC as the metal precursor is essential for the preparation of ultrafine and highly dispersed Ru NPs (1.20 nm in diameter) on a NC support. The as-synthesized Ru/NC-800 displays superior analytical performance for non-enzymatic detection of H2O2 with a low detection limit of 0.468 µM, high sensitivity of 698 µA mM-1 cm-2, excellent linear detection ranging from 0.001 to 10.000 mM, good stability, and high selectivity. The control experiment results indicate that the high-performance of Ru/NC-800 must be ascribed to the ultrasmall and highly dispersed Ru NPs and N-doping, which can supply a higher density of active sites available for H2O2 detection. This study provides a facile strategy to synthesize ultrafine metal NPs and for concomitant production of NC for electrocatalytic non-enzymatic sensing.

Regulating cobalt-nitrogen function centers via Cu incorporation enhances ciprofloxacin destruction through peroxymonosulfate activation.

Metal-nitrogen (M-N) coupling has shown promise as a catalytic active component for various reactions. However, the regulation of heterogeneous catalytic materials with M-N coupling for peroxymonosulfate (PMS) activation to enhance the degradation efficiency and reusability of antibiotics remains a challenge. In this study, an efficient modulation of M-N coupling was achieved through the incorporation of Cu into Co4N to form a Cu-Co4N composite with sea urchin-like morphology assembled by numerous nano-needles using hydrothermal and nitriding processes. This modulation led to enhanced PMS activation for ciprofloxacin (CIP) degradation. The Cu-Co4N/PMS system demonstrated exceptional removal efficiency with a degradation rate of 95.85% within 30 min and can be reused for five time without obvious loss of its initial activity. Additionally, the catalyst displayed a high capacity for degrading various challenging organic pollutants, as well as remarkable stability, resistance to interferences, and adaptability to pH changes. The synergistic effect between Co and Cu facilitated multiple redox cycles, resulting in the generation of reactive oxidized species. The primary active species involved in the catalytic degradation process included 1O2, SO4•-, O2•-, •OH, and e-, with 1O2 and SO4•- playing the most significant roles. The degradation pathways and toxicity of the intermediates for CIP were unveiled. This study offers valuable insights into the regulation of M-N centers for degrading antibiotics through PMS activation.

Nickel-cobalt alloy nanosheet-decorated three-dimensional titanium dioxide nanobelts electrodeposited on titanium meshes for boosting selective nitrate electroreduction to ammonia.

Electrocatalytic nitrate reduction reaction presents a promising avenue for environmentally friendly ammonia (NH3) synthesis and wastewater treatment. An essential aspect to consider is the meticulous design of electrocatalysts. This study explores the utilization of a Ni-Co alloy nanosheet-decorated three-dimensional titanium dioxide (3D-TiO2) nanobelts electrodeposited on titanium meshes (NixCoy@TiO2/TM) for efficient electrocatalytic NH3 production. The optimized Ni1Co3@TiO2/TM electrode achieves a significant NH3 yield of 676.3 ± 27.1 umol h-1 cm-2 with an impressive Faradaic efficiency (FE) of 95.1 % ± 2.1 % in a 0.1 M KOH solution containing 0.1 M NO3- at -0.4 V versus the reversible hydrogen electrode. Additionally, the electrode demonstrates exceptional electrochemical activity for NH3 synthesis in simulated wastewater, delivering an outstanding NH3 yield of 751.6 ± 44.3 umol h-1 cm-2 with a FE of 96.8 % ± 0.4 % at the same potential of -0.4 V. Moreover, the electrode exhibits minimal variation in current density, NH3 yields and FEs throughout the 24-h stability test and the 20-cycle test, demonstrating its excellent stability and durability. This study offers a straightforward electrodeposited approach for the development of 3D-nanostructured alloys as catalysts for NH3 electrosynthesis from nitrates at room temperature.

Boron/nitrogen-trapping and regulative electronic states around Ru nanoparticles towards bifunctional hydrogen production.

Developing a straightforward and general strategy to regulate the surface microenvironment of a carbon matrix enriched with N/B motifs for efficient atomic utilization and electronic state of metal sites in bifunctional hydrogen production via ammonia-borane hydrolysis (ABH) and water electrolysis is a persistent challenge. Herein, we present a simple, green, and universal approach to fabricate B/N co-doped porous carbons using ammonia-borane (AB) as a triple functional agent, eliminating the need for hazardous and explosive functional agents and complicated procedures. The pyrolysis of AB induces the regulation of the surface microenvironment of the carbon matrix, leading to the formation of abundant surface functional groups, defects, and pore structures. This regulation enhances the efficiency of atom utilization and the electronic state of the active component, resulting in improved bifunctional hydrogen evolution. Among the catalysts, B/N co-doped vulcan carbon (Ru/BNC) with 2.1 wt% Ru loading demonstrates the highest performance in catalytic hydrogen production from ABH, achieving an ultrahigh turnover frequency of 1854 min-1 (depending on the dispersion of Ru). Furthermore, this catalyst shows remarkable electrochemical activity for hydrogen evolution in alkaline water electrolysis with a low overpotential of 31 mV at 10 mA cm-2. The present study provides a simple, green, and universal method to regulate the surface microenvironment of various carbons with B/N modulators, thereby adjusting the atomic utilization and electronic state of active metals for enhanced bifunctional hydrogen evolution.

Three-dimensional RuCo alloy nanosheets arrays integrated pinewood-derived porous carbon for high-efficiency electrocatalytic nitrate reduction to ammonia.

Electricity-driven nitrate (NO3-) to ammonia (NH3) conversion presents a unique opportunity to simultaneously eliminate nitrate from sewage while capturing ammonia. However, the Faradaic efficiency and ammonia yield in this eight-electron process remain unsatisfactory, underscoring the critical need for more effective electrocatalysts. In this study, a RuCo alloy nanosheets electrodeposited on pinewood-derived three-dimensional porous carbon (RuCo@TDC) is introduced as a highly-efficient electrocatalyst for the nitrate reduction reaction. The RuCo@TDC catalyst exhibits superior electrocatalytic performance, achieving the highest NH3 yield of 2.02 ± 0.11 mmol h-1 cm-2 at -0.6 V versus the reversible hydrogen electrode (vs. RHE) and the highest Faradaic efficiency of 95.7 ± 0.8 % at -0.2 V vs. RHE in an electrolyte mixture of 0.1 M KOH and 0.1 M KNO3. Furthermore, the Zn-NO3- battery using RuCo@TDC as the cathode provides a maximum power density of 2.46 mW cm-2 and a satisfactory NH3 yield of 1110 µg h-1 cm-2.

Architecture and active motif engineering of N-CoS2@C yolk-shell nanoreactor for boosted tetracycline removal via peroxymonosulfate activation: Performance, mechanism and destruction pathways.

Rational construction of yolk-shell architecture with regulated binding configuration is crucially important but challengeable for antibiotic degradation via peroxymonosulfate (PMS) activation. In this study, we report the utilization of yolk-shell hollow architecture consisted of nitrogen-doped cobalt pyrite integrated carbon spheres (N-CoS2@C) as PMS activator to boost tetracycline hydrochloride (TCH) degradation. The creation of yolk-shell hollow structure and nitrogen-regulated active site engineering of CoS2 endow the resulted N-CoS2@C nanoreactor with high activity for PMS activating toward TCH degradation. Intriguingly, the N-CoS2@C nanoreactor exhibits an optimal degradation performance with a rate constant of 0.194 min-1 toward TCH via PMS activation. The 1O2 and SO4•- species are demonstrated as the dominant active substances for TCH degradation through quenching experiments and electron spin resonance characterization. The possible degradation mechanism, intermediates and degradation pathways for TCH removal over the N-CoS2@C/PMS nanoreactor are unveiled. Graphitic N, sp2-hybrid carbon, oxygenated group (C-OH) and Co species are verified as the possible catalytic sites of N-CoS2@C for PMS activation toward TCH removal. This study offers a unique strategy to engineer sulfides as highly efficient and promising PMS activators for antibiotic degradation.

Alkaline ultrasonic irradiation-mediated boosted H2 production over O/N-rich porous carbon anchored Ru nanoclusters.

Developing efficient catalytic systems to boost hydrogen evolution from hydrolytic dehydrogenation of ammonia borane (AB) is of broad interest but remains a formidable challenge since the widespread usages of hydrogen have been considered as sustainable solutions to ensure future energy security. Herein, we developed an alkaline ultrasonic irradiation-mediated catalytic system with O/N-rich porous carbon supported Ru nanoclusters (NCs) (Ru/ONPC) to considerably boost the catalytic activity for hydrogen production from the hydrolytic dehydrogenation of AB. The uniformly distributed sub-2.0 nm Ru NCs on the ONPC were demonstrated to be efficient catalysts to boost hydrogen generation from the hydrolytic dehydrogenation of AB with the synergistic effect between ultrasonic irradiation and alkaline additive without any additional heating. An ultrahigh turnover frequency (TOF) of 4004 min-1 was achieved in the developed catalytic system, which was significantly higher than that of ultrasound-mediated AB hydrolysis without alkali (TOF: 485 min-1) and alkaline AB hydrolysis (TOF: 1747 min-1) without ultrasound mixing. The alkaline ultrasonic irradiation was beneficial for the cleavage of the OH bonds in the attacked H2O molecules catalyzed by the Ru/ONPC and thus considerably boost the catalytic hydrogen generation from AB. This study provides a tractable and ecofriendly pathway to promote the activity toward AB hydrolysis to release hydrogen.

Facile fabrication of surface vulcanized Co-Fe spinel oxide nanoparticles toward efficient 4-nitrophenol destruction.

Developing efficient modulation strategies to boost the degradation efficiencies of non-noble metal catalysts for toxic phenolic compounds involving peroxymonosulfate (PMS)-based oxidation processes is essential but remains an arduous challenge. This study reports the one-pot construction of in-situ surface vulcanized CoFe2O4 @carbon (Sx-CF@C) to boost the PMS activation for 4-nitrophenol (4-NP) destruction. The direct pyrolysis of an aerogel precursor consisted of cobalt nitrate, ferric nitrate, melamine, and thiourea enables the as-formed Sx-CF@C with hierarchical structure, rich oxygen vacancies, and electron/mass transfer, thereby considerably promoting PMS activation performance of Sx-CF@C toward 4-NP degradation. Specifically, the optimal S0.2-CF@C can achieve a removal efficiency of 99% for 4-NP destruction (20 mg/L) through PMS activation. Meanwhile, the catalyst also has generality to degrade a variety of antibiotic and dye organic pollutants. The radical quenching and electron paramagnetic resonance tests reveal the radical and non-radical activation mechanism in the S0.2-CF@C/PMS system. The degradation pathway for 4-NP destruction over the S0.2-CF@C/PMS system is proposed. This study provides an efficient approach to modulate the PMS activation performance of ferrite spinel materials toward the degradation of acute phenolic compounds.

Sustainable one-pot construction of oxygen-rich nitrogen-doped carbon nanosheets stabilized ultrafine Rh nanoparticles for efficient ammonia borane hydrolysis.

Heteroatom-doped porous carbons that possess large surface areas and well-defined porosity show great promise in heterogeneous catalysis, whereas their syntheses inevitably require complicated steps, hazardous activation and functional reagents, and an inert gas atmosphere. Herein, a one-pot synthetic strategy to oxygen-rich porous nitrogen-doped carbon (OPNC) is developed through pyrolysis of ethylenediamine tetra-acetic acid tetra-sodium in air without any activation and functionalization agents. The as-prepared OPNC with more surface oxygenated groups and mesopores not only benefits synthesis of well-dispersed ultrafine Rh nanoparticles (NPs) with abundant accessible active sites, but also facilitates the diffusion of reactants and avoids mass transfer limitations, thereby considerably contributes to a high performance toward AB hydrolysis. Specifically, the optimal Rh/OPNC exhibits a high activity toward AB hydrolysis with a turnover frequency (TOF) of 433 min-1. The kinetic isotope studies indicate that the cleavage of OH bond in H2O molecules is the rate-determining step (RDS). The Rh/OPNC can be reused for five repetitive cycles with approximately 62% remained activity of the first cycle. The catalytic activity of Rh/OPNC can be further improved with a very high TOF of 1201 min-1 in alkaline solution. This study proposes a simple and sustainable pathway to synthesize efficient catalyst support for depositing metal NPs toward AB hydrolysis.

Hollow Hydrangea-Like CoRu/Co Architecture as an Excellent Electrocatalyst for Oxygen Evolution.

Developing low-cost but efficient electrocatalysts to promote the sluggish kinetics of oxygen evolution from water splitting is essential for hydrogen production. In this study, a hierarchical hollow hydrangea-like CoRu/Co superstructure is constructed through a self-templating method by morphology-controlled pyrolysis of flower-like Ru-doped Co-based layered double hydroxides (LDH). The anchoring of Ru into Co-LDH is the key to the formation of well-defined hydrangea-like three-dimensional superstructure composed of CoRu/Co. The optimized CoRu/Co-M-350 with a low Ru loading of 3.0 wt% exhibits excellent catalytic performances in the oxygen evolution reaction (OER) with low overpotential (η10 =192 mV) and excellent stability for 100 h at 100 mA cm-2 in alkaline media, outperforming the benchmark RuO2 and most reported electrocatalysts. The superior morphology and structural features of CoRu/Co-M-350 provide not only abundant accessible surface sites but also fast mass and electron transfer, thereby promoting OER catalysis. The present study provides a new synthetic route for preparing highly active OER electrocatalysts.

Oxygenated functional group-driven spontaneous fabrication of Pd nanoparticles decorated porous carbon nanosheets for electrocatalytic hydrodechlorination of 4-chlorophenol.

Researchers have been committed to reducing the hazardous pollutants by developing efficient catalysts while ignoring the pollution caused by the use of toxic surface capping agents, reductants and/or organic solvents in the catalyst preparation process. To alleviate such problems, we here report a novel one-step oxygenated functional group-driven electroless deposition strategy to synthesize clean and uniformly distributed Pd nanoparticles (NPs) using porous carbon nanosheets (PCN) as both substrates and reducing agents. It is observed that the oxygenated functional groups enriched PCN possesses a low work function and allows the spontaneous reduction of PdCl42- ions to Pd NPs deposited on the PCN support (Pd/PCN). The particle size of Pd NPs can be flexibly modulated by simply controlling the immersing time and thereby their maximum catalytic performances can be achieved. Specifically, the optimal Pd/PCN-08 with a Pd loading of 3.0 wt% shows an excellent activity with a turnover frequency of 0.38 min-1 for electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP), superior to the previously reported materials. The stability of Pd/PCN-08 for 4-CP ECH is impressive in repetitive cycles. This work proposes a facile and efficient strategy to synthesize high-performance catalysts for detoxifying the hazardous organic pollutants.

Strong electrostatic adsorption-engaged fabrication of sub-3.0 nm PtRu alloy nanoparticles as synergistic electrocatalysts toward hydrogen evolution.

Alloying of Pt with Ru to form ultrafine and well-defined PtRu alloy nanoparticles (NPs) for synergistically electrocatalytic hydrogen evolution is highly desirable but remains a synthetic challenge. Here, we report a strong electrostatic adsorption (SEA)-assisted fabrication of ultrafine and homogeneously distributed PtRu alloy NPs using ethylenediaminetetraacetic acid tetrasodium-derived carbon (EC) as a matrix. The O, N-rich EC with a hierarchically macro/meso/microporous structure and the SEA-assisted formation of the [Ru(bpy)3][PtCl6] complex ensure the successful generation of ultrasmall PtRu alloy NPs (2.93 nm in diameter) with high dispersion. The optimal PtRu/EC-700 delivers excellent electrocatalytic properties with an ultralow overpotential (η10 = 18 mV), robust durability and good long-term stability for the alkaline hydrogen evolution reaction (HER). The ultrasmall PtRu alloy NPs with rich surface sites, the synergistic catalysis effect between Pt and Ru and the hierarchically macro/meso/microporous structure of O, N-rich EC cooperatively enhance the HER performance of PtRu/EC-700. This study provides an easy but effective way to construct metal alloy NPs with an ultrafine size and high dispersity for catalytic applications.

Oxygenated functional group-engaged electroless deposition of ligand-free silver nanoparticles on porous carbon for efficient electrochemical non-enzymatic H2O2 detection.

The construction of metal-carbon nanostructures with enhanced performances using traditional methods, such as pyrolysis, photolysis, impregnation-reduction, etc., generally requires additional energy input, reducing agents and capping ligands, which inevitably increase the manufacturing cost and environmental pollution. Herein, a novel one-step substrate-induced electroless deposition (SIED) strategy is developed to synthesize ligand-free Ag NPs supported on porous carbon (PC) (Ag/PC). The PC matrix enriched with oxygenated functional groups has a low work function and thus a low redox potential compared to that of Ag+ ions, which induces the auto-reduction of Ag+ ions to Ag NPs. The as-synthesized Ag/PC-6 modified electrode can be used as an excellent nonenzymatic H2O2 sensor with a broad linear range of 0.001-20 mM, a low detection limit of 0.729 µM (S/N = 3), and a high response sensitivity of 226.9 µA mM-1 cm-2, outperforming most of the reported sensor materials. Moreover, this electrode can be applied to detect trace amounts of H2O2 in juice and milk samples below the permitted residual level in food packaging and the recovery of H2O2 is 99.6% in blood serum (10%) with good reproducibility. This study proposes an efficient approach for synthesizing a highly active supported Ag electrocatalyst, which shows significant potential for practical applications.

Ultrafine Pd Nanoparticles Supported on Soft Nitriding Porous Carbon for Hydrogen Production from Hydrolytic Dehydrogenation of Dimethyl Amine-Borane.

Simple and efficient synthesis of a nano-catalyst with an excellent catalytic property for hydrogen generation from hydrolysis of dimethyl amine-borane (DMAB) is a missing piece. Herein, effective and recycled palladium (Pd) nanoparticles (NPs) supported on soft nitriding porous carbon (NPC) are fabricated and applied for DMAB hydrolysis. It is discovered that the soft nitriding via a low-temperature urea-pretreatment induces abundant nitrogen-containing species on the NPC support, thus promoting the affinity of the Pd precursor and hindering the agglomeration of formed Pd NPs onto the NPC surface during the preparation process. Surface-clean Pd NPs with a diameter of sub-2.0 nm deposited on the NPC support (Pd/NPC) exhibit an outstanding catalytic performance with a turnover frequency (TOF) of 2758 h-1 toward DMAB hydrolysis, better than many previous reported Pd-based catalysts. It should be emphasized that the Pd/NPC also possesses a good stability without an obvious decrease in catalytic activity for DMAB hydrolysis in five successive recycling runs. This study provides a facile but efficient way for preparing high-performance Pd catalysts for catalytic hydrogen productions.

Pt nanoparticles on Ti3C2Tx-based MXenes as efficient catalysts for the selective hydrogenation of nitroaromatic compounds to amines.

The development of Pt nanocatalysts for the selective hydrogenation of nitroaromatic compounds to the corresponding amines is of great significance to solve the drawbacks associated with a low reserve of Pt. Herein, we develop a protocol for the preparation of a Pt/titanium carbide-based MXene heterostructure for the selective reduction of nitroaromatic compounds. In the heterostructure, well-defined and nano-sized metallic Pt crystallites are uniformly decorated on Ti3C2Tx nanosheets using a mild reducing agent of ammonia borane without additional stabilizing agents. The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) was employed as a model reaction to investigate the catalytic performance of the as-synthesized heterostructure, denoted as Pt/Ti3C2Tx-D-AB. Notably, this catalyst can catalyze the complete conversion of p-CNB to p-CAN with 99.5% selectivity, superior to that of Pt/Ti3C2Tx-D-SB synthesized with sodium borohydride. The high performance of the present catalytic system can be ascribed to the well-dispersed Pt nanoparticles, the abundant surface electron-efficient Pt(0), and the synergistic catalysis between Pt/Ti3C2Tx-D-AB and water. This catalyst also shows generality toward the selective hydrogenation of a series of nitroaromatic compounds to the corresponding amines with high efficiency. The present study provides a strategy to synthesize efficient catalysts for catalytic applications.

Flexible Active-Site Engineering of Monometallic Co-Layered Double Hydroxides for Achieving High-Performance Bifunctional Electrocatalyst toward Oxygen Evolution and H2O2 Reduction.

It is highly desirable but challenging to develop a facile and scalable strategy to synthesize efficient bifunctional electrocatalysts for oxygen evolution and H2O2 reduction by engineering the active site of monometallic-layered double hydroxides (LDHs). Herein, we developed a convenient, efficient, and scalable method for the construction of monometallic Co-LDHs with tunable Con+ (n = 2, 3) concentration by a one-pot solvothermal reaction in a short time (e.g., 2 and 4 h) using only cobalt nitrate and hexamine as raw materials. The catalytic performance of Co-LDHs was mainly determined by the Con+ (n = 2, 3) concentration, which could be simply regulated by tuning the solvothermal time. Combining the joint merits of three-dimensional flowerlike architecture (abundant accessible active sites and a fast electron/mass transport), Co-LDHs-4 with abundant Co3+ species exhibited an excellent electrocatalytic activity for oxygen evolution reaction in terms of a low overpotential at 10 mA cm-2 (η10 = 241 mV) and long-term durability for 70 h at 100 mA cm-2, better than the state-of-the-art IrO2 and most of the reported analogues. Besides, Co-LDHs-2 enriched in Co2+ displayed a superior electrochemical activity for H2O2 detection with a broad linear range (0.002-20 mM), a low detection limit (0.002 mM), and a high response sensitivity (272.02 µA mM-1 cm-2). Therefore, this work opens a new horizon for the rational development of a highly active electrocatalyst with tunable concentrations of active components.