Visible-Light Photocatalytic Degradation Efficiency of Tetracycline and Rhodamine B Using a Double Z-Scheme Heterojunction Catalyst of UiO-66-NH2/BiOCl/Bi2S3.

BiOCl is a promising photocatalyst, but due to its weak visible light absorption capacity and low photogenerated electron-hole pair separation rate, its practical application is limited to a certain extent. In this study, a novel double Z-scheme heterojunction UiO-66-NH2/BiOCl/Bi2S3 catalyst was constructed to broaden the visible light response range and promote high photogenerated hole-electron separation of BiOCl. Its photocatalytic performance is evaluated by dissociating tetracycline (TC) and rhodamine B (RhB) in visible light. The optimal proportion of UiO-66-NH2/BiOCl/Bi2S3 hybrids exhibits the best degradation efficiency of visible light illumination (∼93% in 120 min for TC and ∼98% in 60 min for RhB). The synergistic effect of a large visible light response range and the Z-scheme charge transfer mechanism ensure the excellent visible photocatalytic activity of UiO-66-NH2/BiOCl/Bi2S3. It is proven that h+ and •O2- are the main active substances in the photocatalysis process by active substance capture experiments and electron spin resonance tests. The intermediates and degradation processes are analyzed by high-performance liquid chromatography-mass spectrometry. This study proves that the new UiO-66-NH2/BiOCl/Bi2S3 photocatalyst has great application potential in the field of water pollution degradation and will provide a new idea for the optimization of BiOCl.

Highly bifunctional Rh2P on N,P-codoped carbon for hydrazine oxidation assisted energy-saving hydrogen production.

Highly pure Rh2P nanoparticles on N,P-codoped carbon were synthesized by a simple "mix-and-pyrolyze" method using one kind of low-cost nucleotide as the carbon, nitrogen and phosphorus source, which exhibits excellent bifunctional activity for the hydrogen reduction and hydrazine oxidation reactions, achieving energy-efficient hydrogen production.

Precise regulation of phosphorus in nitrogen-coordinated porous carbon spheres for tunable CO2 electroreduction to syngas.

The production of high-demand syngas with tunable ratios by CO2 electroreduction has attracted considerable research interest. However, it is challenging to balance the evolution performance of H2 and CO with wide H2/CO ratios, while maintaining high efficiency. Herein, nitrogen-coordinated hierarchical porous carbon spheres with varying phosphorus content (PxNC-T) are assembled to regulate syngas production performance. The precise introduction of P modulates the local charge distribution of nitrogen-coordinated carbons, thereby accelerating the protonation process of ∗CO2-to-∗COOH and promoting moderate H∗ adsorption. Specifically, syngas with wide H2/CO ratios (0.60-4.98) is obtained over a low potential range (-0.46 to -0.86 V vs. RHE). As a representative, P1.0NC-900 presents a remarkable current density (-152 mA cm-2) at -1.0 V vs. RHE in flow cells and delivers a decent peak power density (1.93 mW cm-2) in reversible Zn-CO2 batteries. Our work provides valuable insights into the rational design of carbon-based catalysts for CO2 reduction.

One-step construction of hexagonal WO3 nano-shuttles with enhanced lithium storage performance.

In this work, WO3 nanorod-based aggregates and WO3 nano-shuttles were constructed by a facile hydrothermal route. The structure, morphology, element composition and valence state of the formed WO3 samples were characterized using different testing instruments. As the active anode for lithium-ion batteries, the WO3 nano-shuttle electrode can deliver a reversible specific capacity of 614.7 mA h g-1 after 300 cycles at a current density of 500 mA g-1. The excellent electrochemical properties indicate that WO3 nano-shuttles are a prospective anode candidate for high performance lithium-ion batteries.

Highly enhanced hydrazine oxidation on bifunctional Ni tailored by alloying for energy-efficient hydrogen production.

The low-potential hydrazine oxidation reaction (HzOR) can replace the oxygen evolution reaction (OER) and thus assemble with the hydrogen evolution reaction (HER), consequently achieving energy-saving hydrogen (H2) production. Notably, developing sophisticated bifunctional electrocatalysts for HER and HzOR is a prerequisite for efficient H2 production. Alloying noble metals with eligible non-precious ones can increase affordability, catalytic activity, and stability, alongside rendering bifunctionality. Herein, RuNi alloy deposited onto carbon (RuNi/C) was directly prepared by a simple and highly practical co-reduction method, showing excellent performance for HER and HzOR. Interestingly, to achieve 10 mA cm-2, RuNi/C only required an ultralow potential of 24 mV for HER, on par with commercial 20 wt% platinum in carbon (Pt/C), and -65 mV for HzOR, surpassing most reported counterparts. Moreover, the two-electrode electrolyzer only required small operation voltages of 57.8 and 327 mV to drive 10 and 100 mA cm-2, respectively. Driven by a homemade hydrazine (N2H4) fuel cell and solar panel, appreciable H2 yields of 1.027 and 1.406 mmol h-1 were achieved, respectively, exhibiting the energy-saving advantages alongside robust practicability. Moreover, theoretical calculations revealed that alloying with Ru endows bifunctional Ni sites not only with a lower H2O dissociation barrier but also with more favorable H* adsorption alongside the reduced energy barrier between HzOR intermediates.

Structural Construction of WO3 Nanorods as Anode Materials for Lithium-Ion Batteries to Improve Their Electrochemical Performance.

WO3 nanobundles and nanorods were prepared using a facile hydrothermal method. The X-ray diffraction pattern confirms that the obtained samples are pure hexagonal WO3. Transmission electron microscope images detected the gap between the different nanowires that made up the nanobundles and nanorods. As the anode materials of lithium-ion batteries, the formed WO3 nanobundles and WO3 nanorods deliver an initial discharge capacity of 883.5 and 971.6 mA h g-1, respectively. Both WO3 nanostructures deliver excellent capacity retention upon extended cycling. At a current density of 500 mA g-1, the reversible capacities of WO3 nanobundle and WO3 nanorod electrodes are 444.0 and 472.3 mA h g-1, respectively, after 60 cycles.

Pt Nanoparticles Confined in a 3D Porous FeNC Matrix as Efficient Catalysts for Rechargeable Li-CO2/O2 Batteries.

The cathodic product Li2CO3, due to its high decomposition potential, has hindered the practical application of rechargeable Li-CO2/O2 batteries. To overcome this bottleneck, a Pt/FeNC cathodic catalyst is fabricated by dispersing Pt nanoparticles (NPs) with a uniform size of 2.4 nm and 8.3 wt % loading amount into a porous microcube FeNC support for high-performance rechargeable Li-CO2/O2 batteries. The FeNC matrix is composed of numerous two-dimensional (2D) carbon nanosheets, which is derived from an Fe-doping zinc metal-organic framework (Zn-MOF). Importantly, using Pt/FeNC as the cathodic catalyst, the Li-CO2/O2 (VCO2/VO2 = 4:1) battery displays the lowest overpotential of 0.54 V and a long-term stability of 142 cycles, which is superior to batteries with FeNC (1.67 V, 47 cycles) and NC (1.87 V, 23 cycles) catalysts. The FeNC matrix and Pt NPs can exert a synergetic effect to decrease the decomposition potential of Li2CO3 and thus enhance the battery performance. In situ Fourier transform infrared (FTIR) spectroscopy further confirms that Li2CO3 can be completely decomposed under a low potential of 3.3 V using the Pt/FeNC catalyst. Impressively, Li2CO3 exhibits a film structure on the surface of the Pt/FeNC catalysts by scanning electron microscopy (SEM), and its size can be limited by the confined space between the carbon sheets in Pt/FeNC, which enlarges the better contacting interface. In addition, density functional theory (DFT) calculations reveal that the Pt and FeNC catalysts show a higher adsorption energy for Li2CO3 and Li2CO4 intermediates compared to the NC catalyst, and the possible discharge pathways are deeply investigated. The synergetic effect between the FeNC support and Pt active sites makes the Li-CO2/O2 battery achieve optimal performance.

Construction of Nitrogen-Doped Biphasic Transition-Metal Sulfide Nanosheet Electrode for Energy-Efficient Hydrogen Production via Urea Electrolysis.

Urea-assisted hybrid water splitting is a promising technology for hydrogen (H2 ) production, but the lack of cost-effective electrocatalysts hinders its extensive application. Herein, it is reported that Nitrogen-doped Co9 S8 /Ni3 S2 hybrid nanosheet arrays on nickel foam (N-Co9 S8 /Ni3 S2 /NF) can act as an active and robust bifunctional catalyst for both urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), which could drive an ultrahigh current density of 400 mA cm-2 at a low working potential of 1.47 V versus RHE for UOR, and gives a low overpotential of 111 mV to reach 10 mA cm-2 toward HER. Further, a hybrid water electrolysis cell utilizing the synthesized N-Co9 S8 /Ni3 S2 /NF electrode as both the cathode and anode displays a low cell voltage of 1.40 V to reach 10 mA cm-2 , which can be powered by an AA battery with a nominal voltage of 1.5 V. The density functional theory (DFT) calculations decipher that N-doped heterointerfaces can synergistically optimize Gibbs free energy of hydrogen and urea, thus accelerating the catalytic kinetics of HER and UOR. This work significantly advances the development of the promising cobalt-nickel-based sulfide as a bifunctional electrocatalyst for energy-saving electrolytic H2 production and urea-rich innocent wastewater treatment.

Tailoring Nitrogen Species in Disk-Like Carbon Anode Towards Superior Potassium Ion Storage.

Carbon materials, as promising anode candidates for K+ storage due to their low cost, abundant sources, and high physicochemical stability, however, encounter limited specific capacity and unfavorable cycling stability that seriously hinder their practical applications. Herein, a feasible strategy to tailor and stabilize the nitrogen species in unique P/N co-doped disk-like carbon through the Sn incorporation (P/NSn -CD) is presented, which can largely enhance the specific capacity and cycling capability for K+ storage. Specifically, it delivers a high specific capacity of 439.3 mAh g-1 at 0.1 A g-1 and ultra-stable cycling capability with a capacity retention of 93.5% at 5000 mA g-1 over 5000 cycles for K+ storage. The underlying mechanism for the superior K+ storage performance is investigated by systematical experimental data combined with theoretical simulation results, which can be derived from the increased edge-nitrogen species, improved content and stability of P/N heteroatoms, and enhanced ionic/electronic kinetics. After coupling P/NSn -CD anode with activated carbon cathode, the KIHCs can deliver a high energy density of 171.7 Wh kg-1 at 106.8 W kg-1 , a superior power density (14027.0 W kg-1 with 31.2 Wh kg-1 retained), and ultra-stable lifespan (89.7% retention after 30 K cycles with cycled at 2 A g-1 ).

FeP Coated in Nitrogen/Phosphorus Co-doped Carbon Shell Nanorods Arrays as High-Rate Capable Flexible Anode for K-ion Half/Full Batteries.

Building a proper flexible electrode with high cycling stability, rate capacity and initial coulombic efficiency (ICE) for flexible potassium-ion batteries (PIBs) remains a challenge. Herein, nitrogen/phosphorus co-doped carbon coated FeP nanorods arrays on carbon cloth (FeP@N, PC NRs/CC) as high-rate capable flexible self-supporting anode was successfully fabricated. The composite electrode combines the advantages of FeP nanorods arrays (FeP NRs), carbon cloth (CC) and N, P co-doped carbon shell (N, P-C), which comprehensively improves the electrochemical stability of the flexible electrode, while the open space between FeP nanorods can facilitate electrolyte impregnation and enhance K+ transfer, thus effectively elevating the corresponding rate capability. For the FeP@N, PC NRs/CC electrode, it delivers a reversible capacity of 388.8 mA h g-1 at 0.5 A g-1 up to 400 cycles. Even at 1.5 A g-1, it can still achieve a remarkable rate capacity of 346.9 mA h g-1. Moreover, the assembled soft-packed cell can always light the LED lights when it is bent at different angles, which exhibits excellent mechanical flexibility.

Electronic synergy to boost the performance of NiCoP-NWs@FeCoP-NSs anodes for flexible lithium-ion batteries.

Research and development of flexible lithium-ion batteries (LIBs) with high energy density and long cycle life for portable and wearable electronic devices has been a cutting-edge effort in recent years. In this paper, a novel flexible self-standing anode for LIBs is fabricated successfully, in which NiCoP nanowires (NWs) coated with FeCoP nanosheets (NSs) to form core-shell heterostructure arrays are grown on carbon cloth (CC) (designated as NiCoP-NWs@FeCoP-NSs/CC). The obtained NiCoP-NWs@FeCoP-NSs/CC anode integrates the merits of the one-dimensional (1D) NiCoP-NW core and two-dimensional (2D) FeCoP-NS shell and the CC to show a high lithium-ion storage capacity with long-term cycling stability (1172.6 mA h g-1 at 1 A g-1 up to 300 cycles with a capacity retention of 92.6%). The kinetics studies demonstrate that the pseudocapacitive behavior dominates the fast lithium storage of this anode material. For fundamental mechanistic understanding, density functional theory (DFT) analysis is carried out, and manifests that electronic synergy can boost the superior performance of the NiCoP-NWs@FeCoP-NSs/CC anode. The assembled LiFePO4//NiCoP-NWs@FeCoP-NSs/CC full battery gives a discharge capacity of 469.9 mA h g-1 at 0.5 A g-1 after 500 cycles, and even at 2 A g-1, it still can retain 581.5 mA h g-1. Besides, the soft pack full battery can keep the LED lit continuously when it is folded at different angles and maintain brightness for a period of time, highlighting the large application potential of this flexible LIB for wearable electronic devices. This work provides an idea for the design and construction of advanced metal phosphide flexible electrodes for LIBs.

NASICON-Structured LiZr2(PO4)3 Surface Modification Improves Ionic Conductivity and Structural Stability of LiCoO2 for a Stable 4.6 V Cathode.

Lithium cobalt oxide (LCO) as a classic layered oxide cathode for lithium-ion batteries is limited by the cutoff voltage, which only delivers about half of the theoretical capacity (∼4.2 V, 140 mA h g-1). Recently, raising the cutoff voltage to 4.6 V has been considered to further improve its specific capacity. However, LCO suffers from serious phase transition of O3 to H1-3, which leads to dramatic volume change and loss of cobalt, finally resulting in rapid capacity decay. In this work, we introduce the NASICON-structured LiZr2(PO4)3 (LZP), an ion conductor for lithium ion, to modify the surface of LCO by a wet-chemical method. Such a surface modification improves lithium-ion diffusion between the interface of LCO and electrolyte and restrains the O3 to H1-3 phase transition. As a result, the optimized LCO with 1 wt % coating (denoted as LCO@LZP-1%) demonstrates enhanced electrochemical performance in both half-cell and full-cell. To be specific, LCO@LZP-1% delivers a high specific capacity of 161.3 mA h g-1 and increases the capacity retention from 37.8 to 75.1% within 100 cycles. Importantly, the full-cell assembled by LCO@LZP-1% and artificial graphite can exhibit an outstanding energy density of 345.5 W h kg-1 (based on the total mass of cathode and anode).

Niobium Diboride Nanoparticles Accelerating Polysulfide Conversion and Directing Li2S Nucleation Enabled High Areal Capacity Lithium-Sulfur Batteries.

The shuttle effect of polysulfides and Li2S sluggish nucleation are the major problems hampering the further development of lithium-sulfur batteries. The reasonable design for sulfur host materials with catalytic function has been an effective strategy for promoting polysulfide conversion. Compared with other types of transition metal compounds, transition metal borides with high conductivity and catalytic capability are more suitable as sulfur host materials. Herein, a niobium diboride (NbB2) nanoparticle with abundant and high-efficiency catalytic sites has been synthesized by facile solid-phase reaction. The NbB2 with both high conductivity and catalytic nature could regulate 3D-nucleation and growth of Li2S, decrease the reaction energy barrier, and accelerate the transformation of polysulfides. Thus, the NbB2 cathode could retain a high capacity of 1014 mAh g-1 after 100 cycles. In addition, the high initial specific capacities of 703/609 mAh g-1 are also achieved at 5 C/10 C and could run for 1000/1300 cycles within a low decay rate of 0.057%/0.051%. Even with a high sulfur loading up to 16.5 mg cm-2, an initial areal capacity of 17 mAh cm-2 could be achieved at 0.1 C. This work demonstrates a successful method for enhancing the kinetics of polysulfide conversion and directing Li2S nucleation.

SnO2 Anchored in S and N Co-Doped Carbon as the Anode for Long-Life Lithium-Ion Batteries.

Tin dioxide (SnO2) has been the focus of attention in recent years owing to its high theoretical capacity (1494 mAh g-1). However, the application of SnO2 has been greatly restricted because of the huge volume change during charge/discharge process and poor electrical conductivity. In this paper, a composite material composed of SnO2 and S, N co-doped carbon (SnO2@SNC) was prepared by a simple solid-state reaction. The as-prepared SnO2@SNC composite structures show enhanced lithium storage capacity as compared to pristine SnO2. Even after cycling for 1000 times, the as-synthesized SnO2@SNC can still deliver a discharge capacity of 600 mAh g-1 (current density: 2 A g-1). The improved electrochemical performance could be attributed to the enhanced electric conductivity of the electrode. The introduction of carbon could effectively improve the reversibility of the reaction, which will suppress the capacity fading resulting from the conversion process.

Ir nanoclusters/porous N-doped carbon as a bifunctional electrocatalyst for hydrogen evolution and hydrazine oxidation reactions.

One common iridium(III) complex was employed to facilely prepare ultrafine Ir nanoclusters embedded in porous N-doped carbon, which displayed significant bifunctional activity for both hydrogen evolution and hydrazine oxidation under alkaline conditions, enabling energy-efficient hydrogen production.

Integration of bio-inspired lanthanide-transition metal cluster and P-doped carbon nitride for efficient photocatalytic overall water splitting.

Photosynthesis in nature uses the Mn4CaO5 cluster as the oxygen-evolving center to catalyze the water oxidation efficiently in photosystem II. Herein, we demonstrate bio-inspired heterometallic LnCo3 (Ln = Nd, Eu and Ce) clusters, which can be viewed as synthetic analogs of the CaMn4O5 cluster. Anchoring LnCo3 on phosphorus-doped graphitic carbon nitrides (PCN) shows efficient overall water splitting without any sacrificial reagents. The NdCo3/PCN-c photocatalyst exhibits excellent water splitting activity and a quantum efficiency of 2.0% at 350 nm. Ultrafast transient absorption spectroscopy revealed the transfer of a photoexcited electron and hole into the PCN and LnCo3 for hydrogen and oxygen evolution reactions, respectively. A density functional theory (DFT) calculation showed the cooperative water activation on lanthanide and O-O bond formation on transition metal for water oxidation. This work not only prepares a synthetic model of a bio-inspired oxygen-evolving center but also provides an effective strategy to realize light-driven overall water splitting.

Natural DNA-assisted RuP2 on highly graphitic N,P-codoped carbon for pH-wide hydrogen evolution.

Natural DNA was employed for the first time as a phosphorization agent and carbon source to controllably synthesize a RuP2/N,P-codoped carbon composite by a simple "mix-and-pyrolyze" strategy, which displays higher activity for alkaline and acidic HER and neutral activity compared to Pt/C together with outstanding durability.

Carbon-Decorated Na3V2(PO4)3 as Ultralong Lifespan Cathodes for High-Energy-Density Symmetric Sodium-Ion Batteries.

In this work, several carbon-decorated Na3V2(PO4)3 materials (NVP@C-750/800/850) are successfully fabricated using a sol-gel approach and subsequent heat treatment. When NVP@C-800 is used as a cathode, it shows an ultralong cycle life (2000 cycles) at a high rate of 10C, which is superior to the other two electrodes and those of reported NVP@C cathodes in the literature. The excellent results of NVP@C-800 are attributed to its nanostructure and the well-defined conductive carbon layer. The symmetric sodium (Na)-ion battery (SIB) with NVP@C-800 as both a cathode and an anode shows a high capacity at 40 mA g-1 with a voltage plateau of about 1.79 V and energy density of 113 W h kg-1, revealing that NVP@C is of great application prospect.

Yolk-shell structured CoSe2/C nanospheres as multifunctional anode materials for both full/half sodium-ion and full/half potassium-ion batteries.

Transition metal selenides (TMSs) are suitable for SIBs and PIBs owing to their satisfactory theoretical capacity and superior electrical conductivity. However, the large radius of Na+/K+ easily leads to sluggish kinetics and poor conductivity, which hinder the development of SIBs and PIBs. Structure design is an effective method to solve these obstacles. In this study, Co2+ ions combined with glycerol molecules to form self-assembled nanospheres at first, and then they were in situ converted into CoSe2 nanoparticles embedded in a carbon matrix during the selenization process. This structure has three-dimensional ion diffusion channels that can effectively hamper the aggregation of metal compound nanoparticles. Meanwhile, the CoSe2/C of the yolk-shell structure and a large number of pores help alleviate volume expansion and facilitate electrolyte wettability. These structural advantages of CoSe2/C endow it with remarkable electrochemical performances for full/half SIBs and full/half PIBs. The obtained CoSe2/C exhibits superior stability and excellent performance (312.1 mA h g-1 at 4 A g-1 after 1600 cycles) for SIBs. When it is used as an anode material for PIBs, 369.2 mA h g-1 can be retained after 200 cycles at 50 mA g-1 and 248.1 mA h g-1 can be retained after 200 cycles at 500 mA g-1; in addition, CoSe2/C also shows superior rate capacity (186.4 mA h g-1 at 1000 mA g-1). A series of ex situ XRD measurements were adapted to explore the possible conversion mechanism of CoSe2/C as the anode for PIBs. It is worth noting that the full-cell of CoSe2/C//Na3V2(PO4)3@rGO for SIBs and the full-cell of CoSe2/C//PTCDA-450 for PIBs were successfully assembled. The relationship between the structure and performance of CoSe2/C was investigated through density functional theory (DFT).

One-pot thermal decomposition of commercial organometallic salt to Fe2O3@C-N and MnO@C-N for lithium storage.

Iron oxide (Fe2O3) nanoparticles encapsulated in the N-doped carbon framework (Fe2O3@C-N) were synthesized via a one-step thermal decomposition reaction of commercial C10H12FeN2NaO8 (ethylenediaminetetraacetic acid monosodium ferric salt), which can serve as the source of Fe, O, C, and N. As an anode material for lithium storage, the Fe2O3@C-N sample exhibits a reversible capacity of 1072 mA h g-1 after 200 cycles at 0.2 A g-1 and 553 mA h g-1 after 500 cycles at 0.5 A g-1. Furthermore, the synthetic strategy can be simply extended to prepare other similar products, e.g. MnO@C-N and ZnO@C-N. The MnO@C-N anode also shows good cycling performances (915 mA h g-1 after 200 cycles at 0.2 A g-1 and 768 mA h g-1 after 500 cycles at 0.5 A g-1).