Small Gap Research Articles

Failure Inducement Factor Analysis and Optimal Design Method of Ball Bearing Cage for Aviation Motor

In experiments of aviation motor bearings, when the deep-groove ball bearings are subjected to an overturning moment at high speed, it often happens that the rivet on the cage breaks and the debris invades the raceway, resulting in bearing failure. To address the problem of early failure of deep-groove ball bearing cages and rivets in aviation motors, the causes of early failure were analyzed from the aspect of cage design in this study. The influence of the raceway and cage structure parameters on the dynamic contact characteristics of the rolling element and cage under the action of overturning torque were analyzed, the weak link of the cage was determined, and the cage design parameters were optimized. The results show that with an increase in the cage width and pocket radius, the impact force between the ball and cage first decreases and then increases, and the tilt angle of the cage gradually decreases. A larger channel radius and smaller clearance can slow down the interaction between the cage and the rolling element and make the cage run more smoothly. Increasing the thickness of the cage can ensure that the rivet part of the cage is at a low stress level, and the risk of premature fatigue failure at the rivet part can be reduced by maintaining a small gap–fit relationship between the rivet and rivet holes. The research results indicate that the working condition adaptability of the bearing cage for aviation motors can be improved, and the design method for this type of bearing can be enhanced.

Effect of gap size in grass cover on the percentage and rate of dandelion achene germination

AbstractIn Central Europe, Taraxacum officinale Weber ex Wiggers (dandelion) is an economically important admixture in grasslands. Its spread is supported by its ability to germinate in gaps in grass stands. In a 5‐year experiment, we examined the effect of gap size on the germination rate and percentage of dandelion achenes. Each year, achenes were sown in late spring and mid‐summer in 90 square plots of six sizes, ranging from 2.5 × 2.5 cm to 80 × 80 cm. The plots were placed on a 2 × 6 m experimental area covered with low‐cut lawn. The course of germination varied among individual replicates depending on the weather. In each replicate, however, the rate of germination increased, and the percentage of germinated achenes decreased with increasing gap size. Differences in germination paralleled differences in the microclimate on the soil surface of plots where humidity decreased and temperature increased with plot size. The ultimate cause of this difference was the variance among gaps of different sizes in proportion to which the total area of the gap surface is insolated during the day. The colonization of lawns by dandelion is supported by the formation of small gaps in grass stands.

A Facile One-Step Self-Assembly Strategy for Novel Carbon Dots Supramolecular Crystals with Ultralong Phosphorescence Controlled by NH4.

A new methodological design is proposed for carbon dots (CDs)-based crystallization-induced phosphorescence (CIP) materials via one-step self-assembled packaging controlled by NH4 +. O-phenylenediamine (o-PD) as a nitrogen/carbon source and the ammonium salts as oxidants are used to obtain CDs supramolecular crystals with a well-defined staircase-like morphology, pink fluorescence and ultralong green room-temperature phosphorescence (RTP) (733.56ms) that is the first highest value for CDs-based CIP materials using pure nitrogen/carbon source by one-step packaging. Wherein, NH4 + and o-PD-derived oxidative polymers are prerequisites for self-assembled crystallization so as to receive the ultralong RTP. Density functional theory calculation indicates that NH4 + tends to anchor to the dimer on the surface state of CDs and guides CDs to cross-arrange in an X-type stacking mode, leading to the spatially separated frontier orbitals and the through-space charge transfer (TSCT) excited state in turn. Such a self-assembled mode contributes to both the small singlet-triplet energy gap (ΔEST) and the fast inter-system crossing (ISC) process that is directly related to ultralong RTP. This work not only proposes a new strategy to prepare CDs-based CIP materials in one step but also reveals the potential for the self-assembled behavior controlled by NH4 +.

Modeling drivers’ dilemma at unsignalized T-intersections under mixed traffic conditions: A case study from India

Objective At unsignalized T-intersections, right turning drivers from major or minor roads have to accept or reject the available gap and cross the intersection. Poor judgment may arise risk of collision with the major road conflicting vehicles. Subject drivers intending to cross the intersection encounter wide range of gaps. Drivers accept large gaps and reject small gaps. However, drivers experience dilemma over a wide range of gaps. This study aims to examine dilemma experienced by the right turning drivers by modeling gap acceptance and rejection decisions for estimating dilemma zone boundaries on major road. Methods Videographic method was considered for collecting traffic movement data at unsignalized T-intersections. Traffic video data was collected at three specific unsignalized T-intersections with varying degree of channelization. After this, accepted and rejected gaps with different traffic characteristics of offending vehicles (subject drivers) and conflicting vehicles such as speed, distance, vehicle type, etc. for right turning movements were extracted from the video data to analyze gap acceptance and rejection decisions of the drivers and estimate dilemma zone boundaries. Results Gap decisions (acceptance or rejection) were modeled using Generalized Linear Model (GLM) as a function of conflicting vehicle type, speed, and distance from the intersection along with degree of channelization for major and minor roads. The results showed that gap rejection probability increased with increment in conflicting vehicle’s speed and decrement in conflicting vehicle’s distance from the intersection. Dilemma zone boundaries were obtained using developed GLM models by estimating the conflicting vehicle distance from the intersection for 90% and 10% gap rejection probabilities. Dilemma zone boundaries were observed to shift farther from the intersection with increase in vehicle speed and vehicle size. The analysis revealed that subject drivers experienced more dilemma while accepting a gap from major road as compared to minor road. Conclusions This study showed that channelization plays a major role in mitigating dilemma of the subject drivers. Overall, the study identified dilemma zone boundaries for unsignalized T-intersections which may assist the right turning subject drivers to cross the intersection safely.

Defect Engineering of MoTe2 via Thiol Treatment for Type III van der Waals Heterojunction Phototransistor.

Molybdenum ditelluride (MoTe2) nanosheets have displayed intriguing physicochemical properties and opto-electric characteristics as a result of their tunable and small band gap (Eg ∼ 1 eV), facilitating concurrent electron and hole transport. Despite the numerous efforts devoted to the development of p-type MoTe2 field-effect transistors (FETs), the presence of tellurium (Te) point vacancies has caused serious reliability issues. Here, we overcome this major limitation by treating the MoTe2 surface with thiolated molecules to heal Te vacancies. Comprehensive materials and electrical characterizations provided unambiguous evidence for the efficient chemisorption of butanethiol. Our thiol-treated MoTe2 FET exhibited a 10-fold increase in hole current and a positive threshold voltage shift of 25 V, indicative of efficient hole carrier doping. We demonstrated that our powerful molecular engineering strategy can be extended to the controlled formation of van der Waals heterostructures by developing an n-SnS2/thiol-MoTe2 junction FET (thiol-JFET). Notably, the thiol-JFET exhibited a significant negative photoresponse with a responsivity of 50 A W-1 and a fast response time of 80 ms based on band-to-band tunneling. More interestingly, the thiol-JFET displayed a gate tunable trimodal photodetection comprising two photoactive modes (positive and negative photoresponse) and one photoinactive mode. These findings underscore the potential of molecular engineering approaches in enhancing the performance and functionality of MoTe2-based nanodevices as key components in advanced 2D-based optoelectronics.

Spin–Orbit Coupling Free Nonlinear Spin Hall Effect in a Triangle-Unit Collinear Antiferromagnet with Magnetic Toroidal Dipole

We investigate emergent conductive phenomena triggered by collinear antiferromagnetic orderings. We show that an up-down-zero spin configuration in a triangle cluster leads to linear and nonlinear spin conductivities even without the relativistic spin–orbit coupling; the linear spin conductivity is Drude-type, while the nonlinear spin conductivity has Hall-type characterization. We demonstrate the emergence of both spin conductivities in a breathing kagome system consisting of a triangle cluster. The nonlinear spin conductivity becomes larger than the linear one when the Fermi level lies near the region where a small partial band gap opens. Our results indicate that collinear antiferromagnets with triangular geometry give rise to rich spin conductive phenomena.

Electronic instability in pressured black phosphorus under strong magnetic field

In this paper, we have systematically studied the electronic instability of pressured black phosphorous (BP) under strong magnetic field. We first present an effective model Hamiltonian for pressured BP near the Lifshitz point. Then we show that when the magnetic field exceeds a critical value, the nodal-line semimetal (NLSM) state of BP with a small band overlap re-enters the semiconductive phase by re-opening a small gap. This results in a narrow-bandgap semiconductor with a partially flat valence band edge. Moreover, we demonstrate that above this critical magnetic field, two possible instabilities, i.e. charge density wave phase and excitonic insulator (EI) phase, are predicted as the ground state for high and low doping concentrations, respectively. By comparing our results with the experiment (Sun et al 2018 Sci. Bull. 63 1539), we suggest that the field-induced instability observed experimentally corresponds to an EI. Furthermore, we propose that the semimetallic BP under pressure with small band overlaps may provide a good platform to study the magneto-exciton insulators. Our findings bring the first insight into the electronic instability of topological NLSM in the quantum limit.

Solving Sparse Linear Systems Faster than Matrix Multiplication

Can linear systems be solved faster than matrix multiplication? While there has been remarkable progress for the special cases of graph-structured linear systems, in the general setting, the bit complexity of solving an n × n linear system Ax = b is Õ ( n ω ), where ω is the matrix multiplication exponent. Improving on this has been an open problem even for sparse linear systems with poly( n ) condition number. In this paper, we present an algorithm that solves linear systems with sparse coefficient matrices asymptotically faster than matrix multiplication for any ω > 2. This speedup holds for any input matrix A with o ( n ω−1 / log (κ( A ))) non-zeros, where κ( A ) is the condition number of A . Our algorithm can be viewed as an efficient, randomized implementation of the block Krylov method via recursive low displacement rank factorization. It is inspired by an algorithm of Eberly et al. for inverting matrices over finite fields. In our analysis of numerical stability, we develop matrix anti-concentration techniques to bound the smallest eigenvalue and the smallest gap in the eigenvalues of semi-random matrices.

Band engineering for building cascading charge transport channels in ternary CdS-based nanorod array photoanode toward efficient photoelectrochemical H2 generation

A novel CdS/CdSe/Cu2O nanorod array (NRA) photoelectrode with cascading charge transport channels was designed for the first time to remarkedly boot photoelectrochemical (PEC) hydrogen generation under visible light illumination with zero bias. This ternary photoelectrode was constructed by modifying CdS nanorod arrays with n-type CdSe and p-type Cu2O nanoparticles, successively. In this novel photoanode, CdSe and Cu2O with small band gap not merely highly heighten the visible light absorption capacity of CdS, but more importantly integrate with CdS to build cascading charge transport channels at the CdS/CdSe and CdSe/Cu2O interfaces, dramatically facilitating the separation and transport efficiency for photoexcited electron and hole pairs. The CdS/CdSe/Cu2O NRA photoelectrode gains an obvious hydrogen generation rate of 193.2 μmol·h−1, 8.2 times higher than that of bare CdS NRA photoelectrode. The remarkably enhanced PEC hydrogen production for the CdS/CdSe/Cu2O NRA photoanode can be ascribed to effective solar energy utilization and charge carrier separation.

DFT simulations of photovoltaic parameters of dye‐sensitized solar cells with new efficient sensitizer of indolo[3, 2‐b]carbazole complexes

AbstractDeveloping economical and high‐performing sensitizers is crucial in advancing dye‐sensitized solar cells (DSSCs) and optoelectronics. This research paper explores the potential of novel red light‐absorbing organic dyes based on Indolo[3,2‐b]carbazole (ICZ) as the donor applied in co‐sensitizer‐free DSSCs for breakthroughs in photovoltaic (PV) applications. DFT and TD‐DFT based computational methods were employed to calculate the conduction band levels, electron injection capabilities, and power conversion efficiency (PCE) of metal‐free organic dyes (ICZ1–ICZ9) having D‐A‐π‐A architecture. Comprehensive analyses included NBO, DOS, FMO, ICT, MEP, binding energy, and TDM analysis. Quantum chemical calculations of the structural, photochemical, and electrochemical properties, as well as the key parameters, reveals that all the designed dyes could be an excellent candidate for high‐efficiency DSSCs due the small energy gap (2.130–1.947 eV), longer wavelength absorption (759.47–520.63 nm), longer lifetimes (15.65–6.67 ns), a lower ΔGreg (0.29–0.14 eV), a significant dipole moment changes (31.489–16.195D), LHE (0.95‐0.46), the large qCT (0.962–0.689), small DCT (7.657, 4.897 Å), and VOC (1.13–0.86 eV). This quantum simulation showed that, when compared to reference D8, the photovoltaic dyes ICZ8, ICZ2, and ICZ7 are recognized as being eye‐catching. Furthermore, dye@(TiO2)9 cluster model results demonstrate promising prospects for enhancing the photovoltaic (PV) performance of ICZ1–ICZ9 dyes by electron injection and conduction band (CB) engineering. This study will help the experimentalists for developing ICZ‐based PVs as more efficient and sustainable energy solutions.

Recent Progress in Thermally Activated Delayed Fluorescence Photosensitizers for Photodynamic Therapy.

Photodynamic therapy (PDT) is a rapidly growing discipline that is expected to become an encouraging noninvasive therapeutic strategy for cancer treatment. In the PDT process, an efficient intersystem crossing (ISC) process for photosensitizers from the singlet excited state (S1) to the triplet excited state (T1) is critical for the formation of cytotoxic reactive oxygen species and improvement of PDT performance. Thermally activated delayed fluorescence (TADF) molecules featuring an extremely small singlet-triplet energy gap and an efficient ISC process represent an enormous breakthrough for the PDT process. Consequently, the development of advanced TADF photosensitizers has become increasingly crucial and pressing. The most recent developments in TADF photosensitizers aimed at enhancing PDT efficiency for bio-applications are presented in this review. TADF photosensitizers with water dispersibility, targeting ability, activatable ability, and two-photon excitation properties are highlighted. Furthermore, the future challenges and perspectives of TADF photosensitizers in PDT are proposed.

Molecular modeling and cytotoxic activity of newly synthesized benzothiazole-thiazole conjugates

In the dynamic area of drug development, researchers have been urged to uncover and test novel compounds with better effectiveness and fewer side effects in order to find more effective cancer treatments. In this comprehensive study, the synthesis and anticancer efficacy of new benzothiazole-thiazole have been displayed. Initially, a series of benzothiazole-thiazole conjugates 5a-c, 7a-b, and 8 were carefully designed and synthesized from the versatile 6-acetyl-2-phenylsulfonamidobenzothiazole (2), following the guidelines of rational design principles. The DFT/B3LYP approach showed that the synthesized hybrids had a non-planar configuration, where the benzene-sulfonamide group was oriented almost perpendicularly. The tested derivatives exhibited close HOMO-LUMO energies leading to small energy gaps (ΔEH-L = 1.54–2.97 eV). Additionally, the inhibitory effects of the newly synthesized conjugates were tested on four cancer cell lines, including HepG2, HCT-116, MCF-7, and WI38. Conjugates 5a and 8 had strong inhibitory effects on the HCT-116 and MCF-7 cell lines. Additionally, the synthesized conjugates showed inhibitory action against CAIX and CAXII, where conjugate 8 also effectively inhibited both isoforms, as well as, conjugate 5a. Molecular docking analysis was performed to study the binding affinities and interactions of the newly synthesized benzothiazole-thiazole conjugates with the target PDB: 5fl4 protein. Moreover, the ADME outlines of the inspected conjugates were displayed, and conjugates 2 and 6 showed suitable characteristics for GI absorption and minor violations of Lipinski’s rules; thus, they are promising lead compounds.

Understanding Trimipraminium Maleate (TPM) through Spectroscopic, Hirshfeld surface and reactivity analysis: Experimental, DFT and MD studies in different solvents at different temperatures

The electrical and vibrational properties of Trimipraminium maleate (TPM) are reported experimentally and theoretically. Vibrational spectra were recorded, and theoretical wavenumbers were determined and assigned using potential energy distribution. The intra-molecular hydrogen bonding O–H⋯O interaction in maleate is reflected by Hirshfeld surfaces. A small energy gap explains a possible charge transfer via N–H⋯O intermolecular interaction. MD simulations studies were carried out for the TPM at varying temperatures 300, 310, 320, and 330K in three different solvents (water, DMSO, and methanol). Non-covalent interactions are implied from the QTAIM analysis.

Millimeter-Wave and High-Resolution Infrared Spectroscopy of 3-Furonitrile.

The rotational spectrum of 3-furonitrile has been collected from 85 to 500 GHz, spanning the most intense rotational transitions observable at room temperature. The large dipole moment imparted by the nitrile substituent confers substantial intensity to the rotational spectrum, enabling the observation of over 5600 new rotational transitions. Combined with previously published transitions, the available data set was least-squares fit to partial-octic, distorted-rotor A- and S-reduced Hamiltonian models with low statistical uncertainty (σfit < 0.031 MHz) for the ground vibrational state. Similar to its isomer 2-furonitrile, the two lowest-energy vibrationally excited states of 3-furonitrile (ν17, ν24), which correspond to the in-plane and out-of-plane nitrile bending vibrations, form an a- and b-axis Coriolis-coupled dyad. Rotationally resolved infrared transitions (30-600 cm-1) and over 4200 pure rotational transitions for both ν17 and ν24 were fit to a partial-octic, Coriolis-coupled, two-state Hamiltonian with low statistical uncertainty (σfit rot < 0.045 MHz, σfit IR < 6.1 MHz). The least-squares fitting of these vibrationally excited states provides their accurate and precise vibrational frequencies (ν17 = 168.193 164 8 (67) cm-1 and ν24 = 169.635 831 5 (77) cm-1) and seven Coriolis-coupling terms (Ga, GaJ, GaK, Fbc, FbcK, Gb, and Fac). The two fundamental states exhibit a notably small energy gap (1.442 667 (10) cm-1) and an inversion of the relative energies of ν17 and ν24 compared to those of the isomer 2-furonitrile. The rotational frequencies and spectroscopic constants of 3-furonitrile that we present herein provide a sufficient basis for conducting radioastronomical searches for this molecule across the majority of the frequency range available to current radiotelescopes.

Sibling transmission of relationship breakup: Does partnership type matter?

Previous research has highlighted the impact of social network partners on individuals’ attitudes and behaviors and the significant role that siblings often play in providing lifelong support, especially in times of important life events. However, a few studies have examined the intragenerational transmission of divorce risks. Given the increasing prevalence of unmarried cohabitation, however, no study has yet unraveled the link between siblings’ relationship breakups in general, and neither has the impact of siblings’ partnership type and demographic characteristics been investigated. This study aims to understand cross-sibling influence on relationship breakup, including both divorce and separation, and whether sibling similarity in partnership type and demographic traits explain the social influence processes. We used longitudinal data from the Belgian population register and family fixed-effects event history analysis. Partnered individuals ( N = 67,113) and their siblings were followed between 1998 and 2018. The results revealed that an individual’s likelihood of experiencing a union dissolution was lower following that of a sibling. This was particularly pronounced among siblings belonging to the same partnership type (both married or both cohabiting) and close-in-age siblings. For instance, after a sibling’s separation from a cohabitation, cohabiters were at lower odds of dissolving their union than the married, especially when they had a small age gap. The findings indicate that accounting for the time-constant factors originating from the family context, a sibling’s breakup might have a protective impact on one’s own relationship status and duration. The study contributes to the growing knowledge on intragenerational transmission of partnership dissolution.

Microstructural and optical properties of nanostructured Al/Ag co-doped ZnO thin films (AgxAl0.03ZnO0.97-x) by spray pyrolysis for optoelectronic applications

Al/Ag co-doped ZnO (AgxAl0.03ZnO0.97-x, x = 0, 0.02, 0.04, 0.06, 0.08) thin films were prepared using a facile spray pyrolysis deposition route, and their microstructural and optical properties were investigated. Dislocation density reduced and film crystallinity improved with increasing Ag content. This correlated with strain relaxation (∼10−4) and crystallite size enlargement (>23 nm) at high Ag concentrations, as determined by the Scherrer, Williamson-Hall, Halder-Wagner, and Wagner-Agua approximations. The small Urbach energy (<321 meV) and narrow band gap (∼3 eV) observed at low Ag concentration (4 at.%) indicate less structural defects and disorder, and facilitate exciton dissociation with minimum recombination, respectively. The Moss, Herve and Vandamme, and the Ravindra and Gupta models exhibited high correlation between refractive index values (2.09–2.35). Thus, this study demonstrates the enormous potential of Al/Ag co-doping to advance the properties of ZnO films to suit the fabrication of optoelectronic devices, and create opportunities for commercialization.

Comparison between TiO2/rGO and TiO2 with Various Microelectrode Gaps for Biosensor Applications

Sensitive, selective, and stable materials are important to act as an electron transport layer to construct signals in biosensors. Graphene-based biosensors get attention in this industry due to their selective and sensitive properties. We fabricated TiO2/rGO and TiO2 using spin coating in this study. Thermal evaporation deposited the silver. The picoammeter examined the influence of microelectrode gap sizes (50, 100, and 250 μm) on electrical performance. It was revealed that a smaller gap generates better electrical performance. At the smallest gap, the 50μm TiO2 (8.04E-12 A) and TiO2/rGO (2.385E-8 A) at 0.04V. The morphological and chemical analysis supported the electrical behavior of TiO2/rGO and TiO2. These results show that the method used was able to form a TiO2/rGO film that is sensitive to the size of the gap between two microelectrodes.

Characterization of 20 μm Dielectrophoretic Interelectrode Gap for Staphylococcus Aureus Rapid Detection Application

We propose an improvement of dielectrophoresis technique (DEP) by designing, simulating and experiment a 20 μm interelectrode gap for Staphylococcus aureus rapid detection application. In this paper, we use MyDEP simulation for DEP polarization Staphylococcus aureus on frequencies range. COMSOL simulation is utilized for comparison of 20 μm and 80 μm interelectrode gap based on trajectory and velocity of particles for Staphylococcus aureus application. We implied 20 μm interelectrode gap for Staphylococcus aureus application produced higher magnitude DEP force. Which gives accurate trajectory characterization and higher velocity of particle movement. DEP characterization using small interelectrode gap is capable of producing stable and optimum DEP value. It is demanding to distinguish the simulation Staphylococcus aureus using experimental method. DEP technique is important for analysis and characterization of the bacteria. The result show that 20 μm interelectrode gap has higher intensity of electric field which is 1.51 x 10^6 V/m in COMSOL simulation and produced 20.1 m/s for velocity of particle trajectories which is higher compared to 80 μm interelectrode gap. The DEP response was tested on 2.5 MHz, as crossover frequency response was observed on experimental and simulation. Thus, supportsthe capability of 20 μm interelectrode gap for Staphylococcus aureus rapid detection application. Furthermore, DEP characterization can be improvised by focusing on interelectrode gap for characterization among bacteria cells, critical for bacteria detection, manipulation, and isolation.

Lagrangian relaxation for continuous‐time optimal control of coupled hydrothermal power systems including storage capacity and a cascade of hydropower systems with time delays

AbstractThis work considers a short‐term, continuous time setting characterized by a coupled power supply system controlled exclusively by a single provider and comprising a cascade of hydropower systems (dams), fossil fuel power stations, and a storage capacity modeled by a single large battery. Cascaded hydropower generators introduce time‐delay effects in the state dynamics, which are modeled with differential equations, making it impossible to use classical dynamic programming. We address this issue by introducing a novel Lagrangian relaxation technique over continuous‐time constraints, constructing a nearly optimal policy efficiently. This approach yields a convex, nonsmooth optimization dual problem to recover the optimal Lagrangian multipliers, which is numerically solved using a limited memory bundle method. At each step of the dual optimization, we need to solve an optimization subproblem. Given the current values of the Lagrangian multipliers, the time delays are no longer active, and we can solve a corresponding nonlinear Hamilton–Jacobi–Bellman (HJB) Partial Differential Equation (PDE) for the optimization subproblem. The HJB PDE solver provides both the current value of the dual function and its subgradient, and is trivially parallelizable over the state space for each time step. To handle the infinite‐dimensional nature of the Lagrange multipliers, we design an adaptive refinement strategy to control the duality gap. Furthermore, we use a penalization technique for the constructed admissible primal solution to smooth the controls while achieving a sufficiently small duality gap. Numerical results based on the Uruguayan power system demonstrate the efficiency of the proposed mathematical models and numerical approach.

Efficient and economically affordable TiO2 nanotube-based ternary photocatalysts for CO2 conversion boosted by NiO nanoparticles and carbon quantum dots

Photocatalytic CO2 conversion, in general, requires the incorporation of expensive and noble materials to achieve a highly efficient conversion rate. Herein, the TNT/NiO/CQD ternary nanocomposites without any expensive materials and material modification are fabricated for the demonstration of efficient and economically affordable photocatalytic CO2 conversion, to our best knowledge, for the first time. The TNT-based ternary photocatalysts are successfully prepared by a simple anodization and immersion process. The TNT/NiO/CQD ternary nanocomposites produce 1.47 μmol·cm-2·h-1 (≈c.a. 2834 μmol·g-1·h-1) of CH4 as the sole product under AM 1.5 illumination. This is five times higher performance than that of bare TNT and the performance is comparable to that of any other TiO2-based unitary, binary, or ternary photocatalysts. This highly enhanced performance results from effective junction formation between TNT and NiO NP, and the dual role of CQDs as a light absorber and charge transporter/collector in the system. The formation of Z-scheme at the TNT/NiO interface leads to efficient charge transfer via a TiO2/NiO bond. The light absorption of the photocatalysts is enhanced and extended by decorated CQDs due to their small band gap. The charge transfer and collection are further improved by charge depletion at the TNT/CQD interface and the charge transfer at the NiO/CQD interface. This work provides a possible model for the realization of efficient and economically affordable photocatalytic CO2 conversion.