Simulation of the Service Environment and Selection of the Refractory Lining for a Heat Recovery Coke Oven.

A heat recovery coke oven (HRCO) is one of important approaches to achieving a carbon peak and carbon neutrality in China. However, the steady operation of an HRCO is significantly influenced by the internal working conditions and the quality of lining refractories. In this work, a comprehensive study of the internal working conditions of an HRCO was carried out. The results suggest that the partition wall (PW) between the carbonization and combustion chambers is the most vulnerable area, with the corresponding traditional silica bricks inadequate for the service requirements. A reference based on a comparison of the average thermal stress and high-temperature compressive strength is offered for evaluating and selecting silica bricks for the PW. New optimized silica bricks within the reference are verified to be more applicable to the actual working conditions of an HRCO than the traditional silica bricks. As such, this work provides valuable guidance for the optimization and selection of silica bricks for the PW in an HRCO.

Co-utilization of iron ore tailings and coal fly ash for porous ceramsite preparation: Optimization, mechanism, and assessment.

Maximizing the utilization of industrial by-products, such as iron ore tailings (IOTs) and coal fly ash (CFA), is crucial toward sustainable development. This study provides a meticulous insight into the optimization, mechanism, and assessment of the co-utilization of IOTs and CFA for the preparation of porous ceramsite. Micro-CT results revealed that the prepared ceramsite exhibited an exceptional porosity, peaking at 56.98%, with a wide range of pore diameters (3.55-959.10 µm) under optimal conditions (IOTs content at 76%, preheating at 550 °C for 15 min, and sintering at 1177 °C for 14 min), while maintaining good mechanical properties (water adsorption of 1.28%, comprehensive strength of 8.75 MPa, apparent density of 1.37 g/cm3, and bulk density of 0.62 g/cm3). The primary parameters affecting the porosity were identified and ranked as follows: sintering temperature > IOTs content > sintering time. The formation and growth of pores could be attributed to the equilibrium relationship between the liquid-phase surface tension and the gas expansion force, accompanied by pore wall thinning and pore merging. Notably, the prepared ceramsite is both ecologically feasible and economically rewarding, boasting a profit margin of 9.47 $/ton. The comprehensive life cycle assessment (LCA) conducted further highlights the potential of its large-scale implementation for promoting sustainable development. This study provides an innovative strategy for the co-utilization of IOTs and CFA, with advantages such as cost-effectiveness, ecological feasibility and scalability of production.

Built-in Electric Field in Quasi-2D CsPbI3 Perovskites Using High-Polarized Zwitterionic Spacer for Enhanced Charge Separation/Transport.

Two-dimensional (2D) halide perovskites are promising candidates for the fabrication of stable and high-efficiency solar cells. However, the low power conversion efficiency (PCE) of cell devices using 2D perovskites is attributed to reduced charge transport caused by poor organic barrier conductivity. In this study, we propose the use of a high-polarized organic zwitterionic spacer, p-aminobenzoic acid (PABA), to construct novel quasi-2D perovskite structures with enhanced self-driven charge separation and transfer. The NH3+ and COO- groups in PABA generate an aligned electric field, promoting carrier separation and aggregation on the opposite edges of the inorganic layer. This enables efficient in-plane transportation along the inorganic layer. Additionally, PABA intercalated quasi-2D perovskite exhibits improved stability compared with counterparts with diamine cation spacers due to the strong interaction between -COO- and inorganic layers. Our findings suggest that high-polarized organic zwitterionic spacers, with NH3+ and COO- functionality, hold promise for stable and efficient quasi-2D perovskite solar cells.

Energy Level Matching and Band Edge Reconfiguration for Enhanced Charge Transport in Dion-Jacobson 3D/2D Perovskite Heterojunctions.

Generally, the 2D CsPbI3 layer capping on 3D counterparts has been considered as an effective strategy for both enhancing photovoltaic efficiency and stability. However, the intrinsically poor out-of-plane charge transport through the 2D layer remarkably hinders the overall performance of solar devices. To overcome such a challenge, we report the rationally designed 3D-CsPbI3/2D-(PYn)PbI4 (n = 1-4) heterojunctions with desirable energy level matching. It is evidenced that the valence band (VB) edge reconfiguration would occur with the increase of n, accompanied by the VB maximum (VBM) of the 2D component moving down from the higher level above that of the 3D component to the underneath. Consequently, the as-constructed 3D/2D-(PYn)PbI4 (n = 1, 2) heterojunctions exhibit optimal energy level matching, with accelerated transport of holes from 3D to 2D component and limited backflow of electrons. These findings might provide some meaningful insights on the energy level matching in 3D/2D perovskite heterojunctions.

Heterojunction Engineering Enhanced Self-Polarization of PVDF/CsPbBr3 /Ti3 C2 Tx Composite Fiber for Ultra-High Voltage Piezoelectric Nanogenerator.

Piezoelectric nanogenerator (PENG) for practical application is constrained by low output and difficult polarization. In this work, a kind of flexible PENG with high output and self-polarization is fabricated by constructing CsPbBr3 -Ti3 C2 Tx heterojunctions in PVDF fiber. The polarized charges rapidly migrate to the electrodes from the Ti3 C2 Tx nanosheets by forming heterojunctions, achieving the maximum utilization of polarized charges and leading to enhanced piezoelectric output macroscopically. Optimally, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits an excellent voltage output of 160 V under self-polarization conditions, which is higher than other self-polarized PENG previously. Further, the working principle and self-polarization mechanism are uncovered by calculating the interfacial charge and electric field using first-principles calculation. In addition, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits better water and thermal stability attributed to the protection of PVDF. It is also evaluated in practice by harvesting the energy from human palm taps and successfully lighting up 150 LEDs and an electronic watch. This work presents a new idea of design for high-performance self-polarization PENG.

Are formation and adsorption energies enough to evaluate the stability of surface-passivated tin-based halide perovskites?

Surface passivation is one of the effective and widely-used strategies to enhance the stability of halide perovskites with reduced surface defects and suppressed hysteresis. Among all existing reports, the formation and adsorption energies are popularly used as the decisive descriptors for screening passivators. Here, we propose that the often-ignored local surface structure should be another critically important factor governing the stability of tin-based perovskites after surface passivation, but has no detrimental effect on the stability of lead-based perovskites. It is verified that poor surface structure stability and deformation of the chemical bonding framework of Sn-I caused by surface passivation are ascribed to the weakened Sn-I bond strength and facilitated formation of surface iodine vacancy (VI). Therefore, the surface structure stability represented by the formation energy of VI and Sn-I bond strength should be used to accurately screen preferred surface passivators of tin-based perovskites.

Improving Out-of-Plane Charge Mobility and Phase Stability of Dion-Jacobson Lead-Free Perovskites via Intercalating π-Conjugated Aromatic Spacers.

The layered quasi-2D perovskites are recognized as one of the effective strategies to resolve the big problem of intrinsic phase instability of the perovskites. However, in such configurations, their performance is fundamentally limited due to the correspondingly weakened out-of-plane charge mobility. Herein, the π-conjugated p-phenylenediamine (PPDA) is introduced as organic ligand ions for rationally designing lead-free and tin-based 2D perovskites with the aid of theoretical computation. It is evidenced that both out-of-plane charge transport capacity and stability can be significantly enhanced within as-established quasi-2D Dion-Jacobson (DJ) (PPDA)Csn -1 Snn I3 n +1 perovskites. The obviously increased electrical conductivity and reduced carrier effective masses are attributed to the enhanced interlayer interactions, limited structural distortions of diamine cations, as well as improved orbital coupling between Sn2+ and I- ions of (PPDA)Csn -1 Snn I3 n +1 perovskites. Accordingly, by dimension engineering of the inorganic layer (n), the bandgap (Eg ) of quasi-2D perovskites can be linearly tailored toward the suitable Eg (1.387 eV) with optimal photoelectric conversion efficiency (PCE) of 18.52%, representing their great potential toward promising applications in advanced solar cells.

A general thermodynamics-triggered competitive growth model to guide the synthesis of two-dimensional nonlayered materials.

Two-dimensional (2D) nonlayered materials have recently provoked a surge of interest due to their abundant species and attractive properties with promising applications in catalysis, nanoelectronics, and spintronics. However, their 2D anisotropic growth still faces considerable challenges and lacks systematic theoretical guidance. Here, we propose a general thermodynamics-triggered competitive growth (TTCG) model providing a multivariate quantitative criterion to predict and guide 2D nonlayered materials growth. Based on this model, we design a universal hydrate-assisted chemical vapor deposition strategy for the controllable synthesis of various 2D nonlayered transition metal oxides. Four unique phases of iron oxides with distinct topological structures have also been selectively grown. More importantly, ultra-thin oxides display high-temperature magnetic ordering and large coercivity. MnxFeyCo3-x-yO4 alloy is also demonstrated to be a promising room-temperature magnetic semiconductor. Our work sheds light on the synthesis of 2D nonlayered materials and promotes their application for room-temperature spintronic devices.

Ni3 S2 -Ni Hybrid Nanospheres with Intra-Core Void Structure Encapsulated in N-Doped Carbon Shells for Efficient and Stable K-ion Storage.

Iron group metals chalcogenides, especially NiS, are promising candidates for K-ion battery anodes due to their high theoretical specific capacity and abundant reserves. However, the practical application of NiS-based anodes is hindered by slow electrochemical kinetics and unstable structure. Herein, a novel structure of Ni3 S2 -Ni hybrid nanosphere with intra-core voids encapsulated by N-doped carbon shells (Ni3 S2 -Ni@NC-AE) is constructed, based on the first electrodeposited NiS nanosphere particles, dopamine coating outer layer, oxygen-free annealing treatment to form Ni3 S2 -Ni core and N-doped carbon shell, and selective etching of the Ni phase to form intra-core void. The electron/K+ transport and K+ storage reaction kinetics are enhanced due to shortened diffusion pathways, increased active sites, generation of built-in electric field, high K+ adsorption energies, and large electronic density of states at Fermi energy level, resulting from the multi-structures synergistic effect of Ni3 S2 -Ni@NC-AE. Simultaneously, the volume expansion is alleviated due to the sufficient buffer space and strong chemical bonding provided by intra-core void and yolk-shell structure. Consequently, the Ni3 S2 -Ni@NC-AE exhibits excellent specific capacity (438 mAh g-1 at 0.1 A g-1 up to 150 cycles), outstanding rate performances, and ultra-stable long-cycle performance (176.4 mAh g-1 at 1 A g-1 up to 5000 cycles) for K-ion storage.

Exploring Inhibition Mechanism of Si on Cementite Nucleation in Hypereutectoid Steel: Experiments and First-Principles Calculations.

To clarify the influence of Si on cementite nucleation during the solidification of hypereutectoid steel, the types and microstructure of cementite in hypereutectoid steel with various Si concentrations were investigated by X-ray diffraction and scanning electron microscopy. Additionally, the interfacial properties of γ-Fe/Fe3C were studied using the first-principles density functional theory, including work on adhesion, interfacial energy, and electronic structure, with the aim of elucidating the impact mechanism of Si on the cementite nucleation. The results showed that increasing Si concentrations (0-0.42 wt.%) had a negligible effect on the types of cementite in as-cast hypereutectoid steel. However, the average number of cementite lamellae per unit area decreased significantly, indicating that an increase in Si concentrations has an inhibitory effect on cementite nucleation. This can be attributed to the effect of Si on the interfacial properties of γ-Fe (010)/Fe3C (010), where the presence of Si disrupts the charge distribution of the γ-Fe (010)/Fe3C (010) interface and decreases the hybridization of atom orbits on each side of the interface, resulting in a decrease in the interatomic interaction force. This is reflected in the decrease in the work of adhesion (from 6.92 J·m-2 to 6.78 J·m-2) and the increase in the interfacial energy (from -1.42 J·m-2 to -1.31 J·m-2). As a result, the stability of the γ-Fe (010)/Fe3C (010) interface is reduced, making it difficult for the composite structure to form. This indicates that Si doping inhibits cementite nucleation on austenite.

FeNi LDH/V2CTx/NF as Self-Supported Bifunctional Electrocatalyst for Highly Effective Overall Water Splitting.

The development of bifunctional electrocatalysts with efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is still a key challenge at the current stage. Herein, FeNi LDH/V2CTx/nickel foam (NF) self-supported bifunctional electrode was prepared via deposition of FeNi LDH on V2CTx/NF substrate by hydrothermal method. Strong interfacial interaction between V2CTx/NF and FeNi LDH effectively prevented the aggregation of FeNi LDH, thus exposing more catalytic active sites, which improved electrical conductivity of the nanohybrids and structural stability. The results indicated that the prepared FeNi LDH/V2CTx/NF required 222 mV and 151 mV overpotential for OER and HER in 1 M KOH to provide 10 mA cm-2, respectively. Besides, the FeNi LDH/V2CTx/NF electrocatalysts were applied to overall water splitting, which achieved a current density of 10 mA cm-2 at 1.74 V. This work provides ideas for improving the electrocatalytic performance of electrocatalysts through simple synthesis strategies, structural adjustment, use of conductive substrates and formation of hierarchical structures.

Ti3C2Tx (MXene)/Pt nanoparticle electrode for the accurate detection of DA coexisting with AA and UA.

Dopamine (DA), uric acid (UA) and ascorbic acid (AA) are biomolecules widely distributed in the human body and play an important role in many physiological processes. An abnormal concentration of them is associated with various diseases. Thus, the accurate and fast detection of them has been one of the major demands in the healthcare industry. In this study, we demonstrate that Ti3C2Tx/PtNP modified glassy carbon electrodes (GCEs) show a good electrochemical performance in the detection of DA and UA. However, there is no response signal to AA for either the CV or DPV curve due to the electrostatic repulsion between the negatively charged electrode surface and the negatively charged AA. Ti3C2Tx(MXene)/Pt nanoparticles (PtNPs) are prepared by etching Ti3AlC2(MAX) with HF and reducing H2PtCl6 with a NaBH4 aqueous solution. The morphology of Ti3C2Tx/PtNPs is multilayered accordion-like Ti3C2Tx decorated with PtNPs with a diameter of 10-20 nm. Furthermore, it is found that the electrochemical detection of DA will be enhanced by AA. The electrochemical detection rule of AA enhanced DA can be expressed as follows: I(DA+AA) = 0.011216CAA + 0.039950CDA + 1.1175(I(DA+AA) is the peak current of DA coexisting with AA. CAA is the concentration of AA. CDA is the concentration of DA). This can be used as a calibration to correct the concentration of DA when AA and DA coexist. Notably, AA promotes the stability of the electrode because it cleans the oxidation products from the electrode surface in time. In addition, the sensor exhibits good reproducibility and satisfactory recovery results in a real sample.

Construction of CoP2-Mo4P3/NF Heterogeneous Interfacial Electrocatalyst for Boosting Water Splitting.

Developing highly efficient, cost effective and durable bifunctional electrocatalyst remains a key challenge for overall water splitting. Herein, a bifunctional catalyst CoP2-Mo4P3/NF with rich heterointerfaces was successfully prepared by a two-step hydrothermal-phosphorylation method. The synergistic interaction between CoP2 and Mo4P3 heterogeneous interfaces can optimize the electronic structure of active sites, leading to the weak adsorption of H on the Mo sites and the increased redox activity of the Co site, resultantly improving the HER/OER bifunctional catalytic activity. The synthesized CoP2-Mo4P3/NF catalyst exhibits excellent electrocatalytic activity in 1.0 M KOH with low overpotentials of 77.6 and 300.3 at 100 mA cm-2 for HER and OER, respectively. Additionally, the assembled CoP2-Mo4P3/NF||CoP2-Mo4P3/NF electrolyzer delivers a current density of 100 mA cm-2 at a cell voltage of 1.59 V and remains stable for at least 370 h at 110 mA cm-2, indicating the potential application prospective in water splitting.

Ultra-Stable and Durable Piezoelectric Nanogenerator with All-Weather Service Capability Based on N Doped 4H-SiC Nanohole Arrays.

Ultra-stable piezoelectric nanogenerator (PENG) driven by environmental actuation sources with all-weather service capability is highly desirable. Here, the PENG based on N doped 4H-SiC nanohole arrays (NHAs) is proposed to harvest ambient energy under low/high temperature and relative humidity (RH) conditions. Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance. The density of short circuit current of the assembled PENG reaches 313 nA cm-2, which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays. The enhancement can be attributed to the existence of nanohole sidewalls in NHAs. All-weather service capability of the PENG is verified after being treated at -80/80 ℃ and 0%/100% RH for 50 days. The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.

Neodymium-decorated graphene as an efficient electrocatalyst for hydrogen production.

Rare earth (RE) materials such as neodymium (Nd) and others consist of unique electronic configurations which result in unique electronic, electrochemical, and photonic properties. The high temperature (>1100 °C) growth and low active surface areas of REs hinder their use as an efficient electrocatalyst. Herein, different morphologies of Nd were successfully fabricated in situ on the surface of graphene using a double-zone chemical vapor deposition (CVD) method. The morphology of the Nd material on graphene is controlled, which results in the significant enhancement of the large specific surface area and electrochemical active area of the composite material due to the spatial morphology of Nd, thereby improving the hydrogen evolution reaction (HER) performance in an alkaline medium. The significantly enhanced HER activity with an overpotential of 75 mV and a Tafel slope of 95 mV dec-1 at a current density of 10 mA cm-2 is observed in Nd-GF. Mainly, a high specific surface area of ∼2217 cm2 g-1 and the porosity of graphene play major roles in the enhancement of activity. Thus, the present work provides a new strategy for the neodymium engineering synthesis of efficient rare earth-graphene composite electrocatalysts with a high electrochemical active area.

Enhancing the Stability of Orthorhombic CsSnI3 Perovskite via Oriented π-Conjugated Ligand Passivation.

Lead-free orthorhombic CsSnI3 (Bγ-CsSnI3) perovskite has been emerging as one of the potential candidates of photovoltaic materials with superior performance. However, the instability induced by rapid reconstructive phase transition and the oxidation of Sn2+ greatly limits their future application. We thus reported a strategy, oriented π-conjugated ligand passivation, for enhancing the stability of Bγ-CsSnI3, simulated using a Bγ-CsSnI3 slab model based on the first-principles computation. The phase stability was found to be strongly dependent on the orientations of phenylethylammonium (PEA+) ligands. The passivated Bγ-CsSnI3 slab with the ligand molecule axis along [414] was demonstrated as the most stable with the lowest adsorption energy (Eads). Based on this configuration, the calculated formation energies (Eform) of half- and full-monolayer coverage were even more negative than that of yellow phase (Y-) CsSnI3 passivated by PEA+ ligands, verifying the enhanced phase stability. Furthermore, the surface states could be effectively suppressed and the downshifted conduction band minimum (CBM) resulted in a reduced band gap for the completely capped Bγ-CsSnI3. Moreover, the CBM and the valence band maximum (VBM) of the system with complete coverage were respectively donated by the surface and bulky components of the slab, which might benefit the separation and transfer of photogenerated carriers.

Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations.

With superior electrical and thermal properties, aluminum nitride (AlN) exhibits wide application. However, AlN is rather oxygen-sensitive and tends to be oxidized at high temperature. The surface oxidation of AlN remains a major challenge, while the underlying physics of AlN surface oxidation is still elusive. Here, First-principles calculations were performed to study wurtzite AlN(0001) surface oxidation process. The adsorption energy of oxygen was calculated to be site-dependent on the surface with varying O coverage. Calculation indicates that oxygen atoms are preferentially adsorbed at the hollow site (H3) of the AlN(0001) surface regardless of the O coverage. N2 is determined as the dominant gas product. The procedure of N3- removal and the formation of N vacancies (VN) take place step by step. VN plays an accelerating role in the oxidation of AlN, and O2- prefers to occupy the site of VN via consuming the Al p lone-pair electrons and passivating the dangling bond states of Al. An O-Al-O layer is formed when the first Al-N bilayer is fully oxidized, which could be regarded as a precursor of γ-Al2O3. On the basis of our atomic-level simulation, a possible phase transformation mechanism from γ-Al2O3 to α-Al2O3 was further proposed.

Boron doping induced thermal conductivity enhancement of water-based 3C-Si(B)C nanofluids.

In this paper, the fabrication and thermal conductivity (TC) of water-based nanofluids using boron (B)-doped SiC as dispersions are reported. Doping B into the ß-SiC phase leads to the shrinkage of the SiC lattice due to the substitution of Si atoms (0.134 nm radius) by smaller B atoms (0.095 nm radius). The presence of B in the SiC phase also promotes crystallization and grain growth of obtained particles. The tailored crystal structure and morphology of B-doped SiC nanoparticles are beneficial for the TC improvement of the nanofluids by using them as dispersions. Using B-doped SiC nanoparticles as dispersions for nanofluids, a remarkable improvement in stability was achieved in SiC-B6 nanofluid at pH 11 by means of the Zeta potential measurement. By dispersing B-doped SiC nanoparticles in water-based fluids, the TC of the as-prepared nanofluids containing only 0.3 vol.% SiC-B6 nanoparticles is remarkably raised to 39.3% at 30 °C compared to the base fluids, and is further enhanced with the increased temperature. The main reasons for the improvement in TC of SiC-B6 nanofluids are more stable dispersion and intensive charge ions vibration around the surface of nanoparticles as well as the enhanced TC of the SiC-B dispersions.

Superior Photodetectors Based on All-Inorganic Perovskite CsPbI3 Nanorods with Ultrafast Response and High Stability.

Currently, one-dimensional all-inorganic CsPbX3 (X = Br, Cl, and I) perovskites have attracted great attention, owning to their promising and exciting applications in optoelectronic devices. Herein, we reported the exploration of superior photodetectors (PDs) based on a single CsPbI3 nanorod. The as-constructed PDs had a totally excellent performance with a responsivity of 2.92 × 103 A·W-1 and an ultrafast response time of 0.05 ms, respectively, which were both comparable to the best ones ever reported for all-inorganic perovskite PDs. Furthermore, the detectivity of the PDs approached up to 5.17 × 1013 Jones, which was more than 5 times the best one ever reported. More importantly, the as-constructed PDs showed a high stability when maintained under ambient conditions.