基于用户行为的社交网络人格特质识别方法

社交网络已成为人们获取和发布信息的一个重要平台,也是黑客发起网络诈骗的主要场地。大多数黑客在发起网络诈骗之前,首先会判别目标用户的主要人格特点,然后根据主要人格特点制定与其接触的策略。因此,面向社交网络用户的人格特质识别方法的研究对提高用户识别社交网络诈骗能力具有重要意义。提出基于用户的人格特质识别方法。通过构建面向社交网络的人格特质词典提取用户发表或转发文本信息中能反映用户主要人格特质类型的观测值,采用5个具有不同参数值的隐半马尔可夫模型刻画用户在社交网络上发表或转发文本信息的行为过程。在人格特质识别阶段,通过计算每个用户在发表或转发文本信息过程中产生的观测序列相对于模型的平均对数似然概率,以识别用户所属的人格特质类型。在采集的新浪微博数据集上进行实验,结果表明,当假正率为10%时,该方法的总真正率为93.18%,能准确识别用户的人格特质类型。     

Gradient “Single-Crystal” Li-Rich Cathode Materials for High-Stable Lithium-Ion Batteries

As one of the high-energy cathode materials of lithium-ion batteries (LIBs), lithium-rich-layered oxide with “single-crystal” characteristic (SC-LLO) can effectively restrain side reactions and cracks due to the reduced inner boundaries and enhanced mechanical stabilities. However, there are still high challenges for SC-LLO with diverse performance requirements, especially on their cycle stability improvement. Herein, a novel concentration gradient “single-crystal” LLO (GSC-LLO), with gradually decreasing Mn and increasing Ni contents from center to surface, is designed and prepared by combining co-precipitation and molten-salt sintering methods, yielding a capacity retention of 97.6% and an energy density retention of 95.8% within 100 cycles at 0.1 C. The enhanced performance is mostly attributed to the gradient-induced stabilized structure, free of cracks and less spinel-like structure formation after long-term cycling. Furthermore, the gradient design is also beneficial to the safety of LLOs as suggested by the improved thermal stability and reduced gas release. This study provides an effective strategy to prepare high-energy, high-stability, and high-safety LLOs for advanced LIBs.     

Hybrid Catalyst Coupling Zn Single Atoms and CuNx Clusters for Synergetic Catalytic Reduction of CO2

Reverse water-gas shift (RWGS) reaction is the initial and necessary step of CO₂ hydrogenation to high value-added products, and regulating the selectivity of CO is still a fundamental challenge. In the present study, an efficient catalyst (CuZnN_x@C-N) composed by Zn single atoms and Cu clusters stabilized by nitrogen sites is reported. It contains saturated four-coordinate Zn-N₄ sites and low valence CuN_x clusters. Monodisperse Zn induces the aggregation of pyridinic N to form Zn-N₄ and N₄ structures, which show strong Lewis basicity and has strong adsorption for *CO₂ and *COOH intermediates, but weak adsorption for *CO, thus greatly improves the CO₂ conversion and CO selectivity. The catalyst calcined at 700 °C exhibits the highest CO₂ conversion of 43.6% under atmospheric pressure, which is 18.33 times of Cu-ZnO and close to the thermodynamic equilibrium conversion rate (49.9%) of CO₂. In the catalytic process, CuN_x not only adsorbs and activates H₂, but also cooperates with the adjacent Zn-N₄ and N₄ structures to jointly activate CO₂ molecules and further promotes the hydrogenation of CO₂. This synergistic mechanism will provide new insights for developing efficient hydrogenation catalysts.     

Hydrofluoric Acid-Removable Additive Optimizing Electrode Electrolyte Interphases with Li+ Conductive Moieties for 4.5 V Lithium Metal Batteries

High-voltage lithium metal batteries (LMBs) are capable to achieve the increasing energy density. However, their cycling life is seriously affected by unstable electrolyte/electrode interfaces and capacity instability at high voltage. Herein, a hydrofluoric acid (HF)-removable additive is proposed to optimize electrode electrolyte interphases for addressing the above issues. N, N-dimethyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) aniline (DMPATMB) is used as the electrolyte additive to induce PF₆⁻ decomposition to form a dense and robust LiF-rich solid electrolyte interphase (SEI) for suppressing Li dendrite growth. Moreover, DMPATMB can help to form highly Li⁺ conductive Li₃N and LiBO₂, which can boost the Li⁺ transport across SEI and cathode electrolyte interphase (CEI). In addition, DMPATMB can scavenge traced HF in the electrolyte to protect both SEI and CEI from the corrosion. As expected, 4.5 V Li|| LiNi_0.6Co_0.2Mn_0.2O₂ batteries with such electrolyte deliver 145 mAh g⁻¹ after 140 cycles at 200 mA g⁻¹. This work provides a novel insight into high-voltage electrolyte additives for LMBs.     

Grafted MXenes Based Electrolytes for 5V-Class Solid-State Batteries

Polymer blends based solid polymer electrolytes (SPEs), combining the advantages of multiple polymers, are promising for the utilization of 5 V-class cathodes (e.g., LiCoMnO₄ (LCMO)) with enhanced safety. However, severe macro-phase separation with defects and voids in polymer blends restrict the electrochemical stability and ionic migration of SPEs. Herein, inorganic compatibilizer polyacrylonitrile grafted MXene (MXene-g-PAN) is exploited to improve the miscibility of the poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF)/PAN blends and suppress the consolidation of phase particles. The resulting SPE exhibits a high anodic stability with an ionic conductivity of 2.17 × 10⁻⁴ S cm⁻¹, enabling a stable and reversible Li platting/stripping (over 2500 h). The fabricated solid Li‖LCMO cell delivers a 5.1 V discharge voltage with a decent capacity (131 mAh g⁻¹) and cycling performance. Subsequently, the solid all-in-one graphite‖LCMO battery is also constructed to extend the application of MXene based SPEs in flexible batteries. Benefiting from the interface-less design, outstanding mechanical flexibility and stability is achieved in the battery, which can endure various deformations with a low-capacity loss (< ≈10%). This study signifies a significant development on solid flexible lithium ion batteries with enhanced performance, stability, and reliability by investigating the miscibility of polymer blends, benefiting for the design of high-performance SPEs.     

High-Performing Quasi-2D Perovskite Photodetectors with Efficient Charge Transport Network Built from Vertically Orientated and Evenly Distributed 3D-Like Phases

Quasi-two-dimensional (Q-2D) perovskites are emerging as one of the most promising materials for photodetectors. However, a significant challenge to Q-2D perovskites for photodetection is their insufficient charge transport ability, which is mainly attributed to their hybrid low-dimensional n-phase structure. This study demonstrates that evenly-distributed 3D-like phases with vertical orientation throughout the film can greatly facilitate charge transport and suppress charge recombination, outperforming the prevalent phase structure with a vertical dimension gradient. Based on such a phase structure, a Q-2D Ruddlesden−Popper perovskite self-powered photodetector achieving a combination of exceptional figures-of-merit is realized, including a responsivity of 0.45 AW⁻¹, a peak specific detectivity of 2.3 × 10¹³ Jones, a 156 dB linear dynamic range, and a rise/fall time of 2.89 µs/1.93 µs. The desired phase structure is obtained by utilizing a double-hole transport layer (HTL), combining hydrophobic PTAA and hydrophilic PEDOT: PSS. Besides, the dependence of the hybrid low-dimensional phase structure is also identified on the surface energy of the buried HTL substrate. This study gives insight into the correlation between Q-2D perovskites’ phase structure and performance, providing a valuable design guide for Q-2D perovskite-based photodetectors.     

A Polymer Defect Passivator for Efficient Hole-Conductor-Free Printable Mesoscopic Perovskite Solar Cells

Due to the low cost and excellent potential for mass production, printable mesoscopic perovskite solar cells (p-MPSCs) have drawn a lot of attention among other device structures. However, the low open-circuit voltage (V_OC) of such devices restricts their power conversion efficiency (PCE). This limitation is brought by the high defect density at perovskite grain boundaries in the mesoporous scaffold, which results in severe nonradiative recombination and is detrimental to the V_OC. To improve the perovskite crystallization process, passivate the perovskite defects, and enhance the PCE, additive engineering is an effective way. Herein, a polymeric Lewis base polysuccinimide (PSI) is added to the perovskite precursor solution as an additive. It improves the perovskite crystallinity and its carbonyl groups strongly coordinate with Pb²⁺, which can effectively passivate defects. Additionally, compared with its monomer, succinimide (SI), PSI serves as a better defect passivator because the long-chained macromolecule can be firmly anchored on those defect sites and form a stronger interaction with perovskite grains. As a result, the champion device has a PCE of 18.84%, and the V_OC rises from 973 to 1030 mV. This study offers a new strategy for fabricating efficient p-MPSCs.     

Catalytically Induced Robust Inorganic-Rich Cathode Electrolyte Interphase for 4.5 V Li||NCM622 Batteries

Tailoring inorganic components of cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) is critical to improving the cycling performance of lithium metal batteries. However, it is challenging due to complicated electrolyte reactions on cathode/anode surfaces. Herein, the species and inorganic component content of the CEI/SEI is enriched with an objectively gradient distribution through employing pentafluorophenyl 4-nitrobenzenesulfonate (PFBNBS) as electrolyte additive guided by engineering bond order with functional groups. In addition, a catalytic effect of LiNi_0.6Mn_0.2Co_0.2O₂ (NCM622) cathode is proposed on the decomposition of PFBNBS. PFBNBS with lower highest occupied molecular orbital can be preferentially oxidized on the NCM622 surface with the help of the catalytic effect to induce an inorganic-rich CEI for superior electrochemical performance at high voltage. Moreover, PFBNBS can be reduced on the Li surface due to its lower lowest unoccupied molecular orbital , increasing inorganic moieties in SEI for inhibiting Li dendrite generation. Thus, 4.5 V Li||NCM622 batteries with such electrolyte can retain 70.4% of initial capacity after 500 cycles at 0.2 C, which is attributed to the protective effect of the excellent CEI on NCM622 and the inhibitory effect of its derived CEI/SEI on continuous electrolyte decomposition.     

Bifunctional Edge-Rich Nitrogen Doped Porous Carbon for Activating Oxygen and Sulfur

Oxygen reduction reaction (ORR) and sulfur reduction reaction (SRR) play key roles in advanced batteries. However, they both suffer from sluggish reaction kinetics. Here, an interesting nitrogen doped porous carbon material that can simultaneously activate oxygen and sulfur is reported. The carbon precursor is a nitrogen containing covalent organic framework (COF), constituting periodically stacked 2D sheets. The COF structure is well preserved upon pyrolysis, resulting in the formation of edge-rich porous carbon with structure resembling stacked holey graphene. The nitrogen containing groups in the COF are decomposed into graphitic and pyridinic nitrogen during pyrolysis. These edge sites and uniform nitrogen doping endow the carbon product with high intrinsic catalytic activities toward ORR and SRR. The COF derived carbon delivers outstanding performances when assembling as cathodes in the Li-S and Li-O₂ batteries. Simultaneous activation of oxygen and sulfur also enables a new battery chemistry. A proof-of-concept Li-S/O₂ hybrid battery is assembled, delivering a large specific capacity of 2,013 mAh g⁻¹. This study may inspire novel battery designs based on oxygen and sulfur chemistry.     

Vacancy Manipulation Induced Optimal Carrier Concentration,Band Convergence and Low Lattice Thermal Conductivity in Nano-Crystalline SnTe Yielding Superior Thermoelectric Performance

Synergetic optimization of electrical and thermal transport properties is achieved for SnTe-based nano-crystalline materials. Gd doping is able to suppress the Sn vacancy, which is confirmed by positron annihilation measurements and corresponding theoretical calculations. Hence, the optimal hole carrier concentration is obtained, leading to the improvement of electrical transport performance and simultaneous decrease of electronic thermal conductivity. In addition, the incremental density of states effective mass m* in SnTe is realized by the promotion of the band convergence via Gd doping, which is further confirmed by the band structure calculation. Hence, the enhancement of the Seebeck coefficient is also achieved, leading to a high power factor of 2922 µW m⁻¹ K⁻² for Sn_0.96Gd_0.04Te at 900 K. Meanwhile, substantial suppression of the lattice thermal conductivity is observed in Gd-doped SnTe, which is originated from enhanced phonon scattering by multiple processes including mass and strain fluctuations due to the Gd doping, scattering of grain boundaries, nano-pores, and secondary phases induced by Gd doping. With the decreased phonon mean free path and reduced average phonon group velocity, a rather low lattice thermal conductivity is achieved. As a result, the synergetic optimization of the electric and thermal transport properties contributes to a rather high ZT value of ≈1.5 at 900 K, leading to the superior thermoelectric performance of SnTe-based nanoscale polycrystalline materials.