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Sandwich-like m-Ti3C2/Fe3O4 composites derived from electrostatic assembly exhibit highly effective electromagnetic (EM) wave absorption capacity. We demonstrate the influence of regulating electron hopping behaviors on EM characteristics and absorption performance.

This work provides a reliable view for understanding the phase and composition of as-prepared Na3V2(PO4)2F3, showing that the proper introduction of oxygen substitution for fluorine is beneficial to the electrochemical performance.

The selectivity of electrochemical reduction of CO2 to CO can be effectively improved by doping Sn into a CuAg film.

Graphene-based 2D materials have shown extraordinary promise in electrochemical energy storage, owing to their high electrochemical activity, fast carrier mobility, and large electronic conductivity. However, low specific capacity ( 5 mAh cm−2). The highly interpenetrating graphene oxide network in the HAGO/Co@CN electrode accelerates electronic transport. In addition, benefiting from the advanced layered architecture, the HAGO/Co@CN electrode exhibits excellent structural stability and thickness-independent electrochemical performances. By systematically adjusting the orientation of GO/Co@CN nanosheets inside electrode to optimize the electron/ion transmission to deliver high areal capacity and high-rate capability at high mass loading. More importantly, a designed full cell with NCM622 cathode and HAGO/Co@CN anode shows ultrahigh capacity retention of >98% at 1 C after 500 cycles with a commercial-level reversible capacity of 2.3 mAh cm−2.

The lithium metal anode (LMA) is considered one of the most promising anode materials because of its highest specific capacity and lowest reduction potential. However, the application of LMA is hindered by uncontrollable dendrite growth, an unstable interphase, and large volume fluctuations. The optimization of electrolytes and the introduction of artificial interphase layers are promising ways to address these issues on the interface between electrolyte and electrode. As an important component in electrolyte engineering and surface modification, functional polymers are attracting great attention. This review aims to provide a conceptual understanding of functional polymers in reducing dendrite growth, building a stable interphase, and accommodating volume change. There is a particular focus on the detailed interfacial chemistry and Li+ ion transport/transfer mechanism. Finally, perspectives on the current challenges and research directions for functional polymers for advanced LMAs are presented.

Metallic phase molybdenum disulfides exhibit impressive charge transfer ability and this has made them interesting candidates for use in the field of nano-science and heterogeneous catalysis. However, the synthesis of 100% pure bare 1T-MoS2 is difficult due to its kinetic instability. In the past, the phase transition mechanism from a semiconductor (2H) to a metallic (1T) phase has been explained only by theoretical calculations. Herein, we used magnetron sputtering to deposit a series of MoS2 films containing various metal heteroatoms as the dopants. Density functional theory (DFT) calculations revealed that the single-doped Cu-MoS2, Au-MoS2, Ag-MoS2, and Al-MoS2 exhibited distinct phase transitions compared to Cr-MoS2, Hf-MoS2, Ta-MoS2, and Zr-MoS2, due to the introduction of additional charge. Furthermore, the hydrogen evolution reaction (HER) activities of the series of MoS2 films were explored, and the adsorption free energy of H atoms was evaluated by DFT calculations.

Aqueous-based Zn–air and Al–air batteries are considered to be promising post-lithium energy storage technologies owing to their safety, environmental friendliness, affordability, and high energy density. Nevertheless, traditional liquid Zn–air and Al–air batteries have problems such as volatilization and leakage, as well as the realization of miniaturized, portable, and wearable electronic devices. The practice of optimizing the battery structure by replacing the flowing electrolyte with a solid type has emerged and made significant progress in the past ten years. Herein, this review provides a guiding and comprehensive summary of the basic understanding and manufacturing ideas of the solid electrolyte for Zn–air and Al–air batteries. First, two types of alkaline solid electrolytes are distinguished, including alkaline anion exchange membranes (AAEMs) and gel polymer electrolytes (GPEs). Then, three sorts of major framework materials (i.e., artificial organic polymer, biomass materials, and inorganic materials) are reviewed and discussed. Most importantly, the latest research progress and improvement strategies to enhance the electrolyte membrane performances involving conductivity, mechanical properties, and electrochemical stability are also highlighted. Finally, challenges and prospects for the future development of alkaline solid electrolytes are emphasized.

Here we prepare a hexagonal boron nitride (h-BN)–polyethylene oxide composite polymer electrolyte via a convenient casting method, which shows high mechanical strength. Meanwhile, the electrochemical properties (electrochemical window and lithium ion transference number) are enhanced but the ionic conductivity of the h-BN composite electrolyte is decreased after adding h-BN. Density functional theory (DFT) calculation results show that a stronger binding effect is observed between TFSI− and BN, compared to that between Li+ and BN. Molecular dynamics (MD) simulations are also utilized to study the mechanism behind the enhanced Li ion diffusion by h-BN addition. Li+ diffusion in PEO/LiTFSI/BN is lower than that in the PEO/LiTFSI system, but the diffusion of TFSI− exhibits a more significant decline rate in the presence of BN. This indicates that the presence of BN suppresses anion motion and enhances selectivity in Li+ transport. Thus, the PEO/LiTFSI/h-BN composite electrolyte exhibits higher Li ion conductivity but lower anion diffusivity than the PEO/LiTFSI system. Hence the h-BN composite polymer electrolyte in a Li/Li symmetric battery provides a long cycling time of 430 h at 0.2 mA cm−2. A Li metal/LiFePO4 full battery with the PEO/LiTFSI/h-BN composite electrolyte also works more efficiently for long-term cycling (140 cycles) than a filler-free PEO based electrolyte (39 cycles).

Defect and interface engineering is a powerful strategy to tune the electronic structure and adsorption behavior of electrocatalysts, boosting the performance of the electrocatalytic CO2 reduction reaction (eCO2RR). Herein, we construct a hybrid electrocatalyst, Bi2S3–Bi2O3@rGO, with a large amount of defects (oxygen vacancies etc.) and a specific interface between bismuth sulfide (Bi2S3) and bismuth oxide (Bi2O3) by a partial precipitation conversion method. Both experimental results and theoretical calculations reveal that the Bi2S3–Bi2O3 interface drastically lowers the formation energy of HCOO*, in favor of the production of formate (HCOOH) over CO, promoting the conversion of CO2 to HCOOH. The as-prepared electrocatalyst shows excellent electrocatalytic activity to generate HCOOH with a high faradaic efficiency of over 90% and a low overpotential of 700 mV, as well as excellent durability for more than 24 h.

A solid polymer electrolyte is expected to be useful for safe and high energy density lithium-metal batteries owing to its good flexibility and high degree of safety. The development of a polyethylene oxide (PEO) based solid electrolyte is still restrained by low ionic conductivity and unsatisfactory mechanical strength. Since MnO2 could combine with PEO chains and Li ions could undergo long-range migration on MnO2 nanosheets, MnO2 nanoflakes are chosen as fillers to improve the electrochemical and mechanical properties of a solid polymer electrolyte. A PEO/MnO2 composite solid polymer electrolyte (CSPE) displays a higher lithium ion transference number (0.378), higher ionic conductivity (1.5 times higher at 60 °C) and better tensile strength (2.3 times) than a PEO solid electrolyte. Density functional theory calculations reflect the fact that the binding energy between the PEO/Li complex and MnO2 is small and there is easy desorption of Li from PEO and migration on MnO2 nanosheets, indicating enhanced lithium ion transport in the electrolyte system. A solid-state lithium metal battery using a PEO/MnO2 CSPE delivers higher capacity (143.5 mA h g−1 after 300 cycles) than an electrolyte without fillers (61.2 mA h g−1 after 90 cycles). Soft-package lithium metal batteries with an MnO2 CSPE reveal high safety after cutting, nail and bending tests.

In this work, orthorhombic CoSe2 is fabricated by nitrogen doping into a cubic CoSe2 structure, in which the crystalline phase undergoes transformation. The doped atoms lead to the rotation of the Se22− group, and then the faults of phase change can be observed. Thus, the reverse phase transformation provides an opportunity to study the aspects of element doping and phase change on photocatalytic CO2 reduction simultaneously. The phase change material of N-doped orthorhombic CoSe2 shows high activity toward the photoconversion of CO2 to CO, and the average production rate of CO is up to 1.66 × 104 μmol h−1 g−1 in the first 3 hours, being twice as efficient as that of cubic CoSe2. Intermediate COOH* is detected by in situ infrared spectroscopy and theoretical calculations are also conducted to reveal the intrinsic impact of the doping element on the photosplitting of CO2.

Although NiFe-based (oxy)hydroxides species have been recognized as one of the most promising water oxidation catalysts, existing synthetic methods are difficult to fulfill the requirements of catalytic performance, lifetime and large-scale production. Here, we develop a scaled-up and simple dual-oxidative etching strategy for introducing metallic copper into a NiFe hydroxide nanosheet array on a Ni foam electrode (Cu–NiFe LDH/NF) for the oxygen evolution reaction. This dual-oxidation strategy is achieved via a galvanic–corrosion reaction between the metallic Ni template and ions with higher reduction potential (Fe3+ and Cu2+). The as-prepared electrode exhibits unparalleled activity toward water oxidation with an overpotential of 185 mV at a current density of 10 mA cm−2 and Tafel slope of merely 30 mV dec−1, respectively. More importantly, this inexpensive and simple manufacturing technique affords the Cu–NiFe LDH/NF electrode excellent activity retention for over 1200 hours.

In this study, we report a two dimensional network through the combination of CoO nanoparticles and nitrogen doped carbon nanotubes (CoO-NCNTs) derived from a lamellar coordination polymer, ([CoII(2,3-chedc)(DABCO)0.5]), (2,3-chedc, cyclohexene-2,3-dicarboxylate; DABCO, 1,4-diazabicyclo[2.2.2]octane). During the pyrolysis of this two dimensional metal–organic framework (MOF), the NCNTs emerge accompanied with the catalysis of CoO nanoparticles and are connected to form two dimensional networks. The cobalt oxide particles are encapsulated and remain at the apical position of NCNTs. Due to the specific architecture and high content of CoO in the composite, it possesses great potential for lithium/sodium storage. Noticeably, high capacity and super long calendar life of 2000 cycles with only 0.0063% capacity loss per cycle is acquired for Li storage at a current density of 500 mA g−1. In addition, it also exhibits good sodium storage performance, which delivers a high capacity of 450 mA h g−1, and long cycling capability for 300 cycles with a capacity loss of 0.066% at a rate of 500 mA g−1. Remarkable performance emphasizes the great potential of the two dimensional MOFs for extensive utilizations in energy storage and transfer processes.

The hydrogen evolution reaction (HER) is a promising clean and renewable energy source. Thus, efficient and inexpensive electrocatalysts for the HER have attracted considerable attention. Here, we report a two-step method for the synthesis of a unique CoMoO4–Co2Mo3O8 heterostructure. The CoMoO4–Co2Mo3O8 heterostructure exhibited superior HER activity that included a low overpotential of 57 mV, a Tafel slope of 55 mV dec−1 in a 1 M KOH solution, and excellent long-term stability given its high intrinsic activity and superior conductivity. Density functional theory calculations indicated that CoMoO4 and Co2Mo3O8 synergistically optimized electron distribution to reduce hydrogen adsorption energy and significantly enhance electrocatalytic activity. Our work may provide novel ideas for improving the HER performance of valence-rich transition element oxides.

Metal nitride materials are considered as promising candidates for next-generation lithium-ion secondary battery anode materials owing to their high electrical conductivity and attractive theoretical capacity. In this paper, we reported a synthesis method to grow ultrafine Ni3N–Co3N nanoparticles on carbon nanotubes (Ni3N–Co3N@CNTs) via a simple hydrothermal reaction and post-ammonization treatment. By virtue of such a unique structure and component, especially the abundant phase boundaries between Ni3N and Co3N, when used as anodes for lithium-ion batteries (LIBs), the resultant composites delivered reversible discharge capacity of 553.26 mA h g−1 even after 600 cycles at a current density of 0.4 A g−1. This reversible capacity was remarkably higher than the theoretical capacities of both Ni3N (424.3 mA h g−1) and Co3N (421.0 mA h g−1). We believe that this study will provide a new idea to design high-performance anode materials for LIBs via constructing abundant phase boundaries between different components in composites.

Solid polymer electrolytes (SPEs) are expected to improve the safety and performance of lithium ion batteries (LIB). However, the low ionic conductivity limit the further application of PEO based electrolytes. Herein, g-C3N4 nanosheets is proposed as a novel filler for PEO based electrolytes. The addition of g-C3N4 improves the electrical properties (ionic conductivity, lithium ion transference number and electrochemical window), mechanical properties and thermal stability of the composite electrolyte. The two-dimensional g-C3N4 forms an effective ion transport network in the composite electrolyte. In addition, the surface atoms of the g-C3N4 interact with groups in the lithium salt, promoting further dissociation of the lithium salt. Furthermore, the all solid state batteries assembled by the g-C3N4 composite electrolyte exhibited good cycle performance at 60 °C (remained at 155 mA h g−1 after 100 cycles). Owing to the simple synthesis and environmental friendliness, g-C3N4 nanosheets has a certain practical prospect as a filler for solid polymer electrolytes.

While non-noble transition metal nanoparticles are widely explored in the field of solar energy harvesting and conversion at high temperatures, their high tendency to diffuse and oxidize may cause a substantially reduced lifetime of devices. To address this issue, herein, we demonstrate that Ni nanoparticles individually encapsulated in a densified ceramic shell, achieved by a SiO2 coating and a subsequent densification process, possess significantly enhanced stability at high temperatures. Ni diffusion is effectively prevented at temperatures as high as 800 °C, and the oxidation of the Ni nanoparticles is suppressed at 500 °C when exposed to air. A spectrally selective absorbing film fabricated with these densified Ni@SiO2 NPs exhibits high optical absorption with reflectance

Solar steam generation is an attractive technology for harvesting solar energy. Many efforts have been devoted to developing absorbers with increased solar energy absorption efficiency. However, little attention has been paid to the thermal radiation loss of the absorbers, which is equally important for achieving high solar-steam efficiency. To address this issue, herein, we report a solar harvesting strategy by introducing a nickel-nanoparticle-based spectrally selective absorber that possesses high and broadband absorption in the solar irradiation region but minimal thermal emittance at long-infrared wavelengths. Nickel nanoparticles are encapsulated in silica and carbon nanoshells, which are then assembled in an orderly manner on an infrared reflector to form a harvesting structure of graded refractive indices. As a result, high solar absorptance (α ≈ 0.93) but low thermal emittance (e ≈ 0.096) has been achieved. An interfacial evaporation system with this unique absorber demonstrates a boosted water evaporation rate of 1.52 kg m−2 h−1 under 1 sun, which is ∼5 times the value for water alone, making it one of the best absorbers for solar steam generation applications. The combined advantages of high efficiency and durability suggest its potential for industrial water purification and desalination applications.

Transition metal vanadates have gained significant attention as high performance anode materials for lithium ion batteries (LIBs). Herein, we successfully fabricated a novel hierarchical hybrid nanostructure of ordered mesoporous carbon (CMK-3) supported Ni3V2O8 composites (Ni3V2O8@CMK-3) through a facile hydrothermal method and a post-calcination process for the first time. Within such a hierarchical hybrid structure, short intercrossed Ni3V2O8 nanorods are firmly anchored onto the external surface of CMK-3 and ultrafine Ni3V2O8 nanoparticles are embedded in the internal channels of CMK-3. Benefitting from their robust porous structure and excellent conductive characteristic, the as-prepared hierarchical hybrid Ni3V2O8@CMK-3 composites exhibit long-term cycle stability with a high reversible capacity of 945.9 mA h g−1 after 200 cycles at a current density of 500 mA g−1 and superior high-rate capability (161.5 mA h g−1 when cycled at 20 A g−1) when used as a promising anode for LIBs.

Sodium titanate (Na2Ti3O7) has been proved to be a potential anode material for sodium-ion batteries. However, its poor rate capability and low electrical conductivity has seriously hindered its application. Therefore, a unique red blood cell-like hollow carbon sphere supported Na2Ti3O7 sodium titanate nanosheet structure (Na2Ti3O7@RHCS) was designed here, which can both improve the electrical conductivity and preserve the structural stability, thus obtaining high rate performance. In addition, the red blood cell-like spherical structure can greatly increase the compacted density via a dense packing mode just like red blood cells stacked together one by one. Meanwhile, the ultrathin nanosheet-like morphology of Na2Ti3O7 could further increase the number of active reaction sites and reduce the diffusion path of sodium ions during the charge–discharge process. This well-designed material exhibits a good cycling performance: a reversible capacity of 110.46 mA h g−1 at 5C and 45.71 mA h g−1 at 50C.

Carbon-based anode materials are faced with challenges in rechargeable sodium-ion batteries (SIBs). In this paper, we describe a substrate, N-doped amorphous micron-sized carbon ribbons (AMCRs), derived from biomass from raupo, on which few-layer MoS2 nanosheets with enlarged interlayer spacings (≈0.75 nm) are anchored. The nitrogen-enriched AMCRs are economically prepared by a single pyrolysis step. The uniform distribution of nitrogen atoms enables ultra homogeneous growth of the MoS2 nanosheets on the AMCRs. The as-prepared AMCRs@MoS2 composite is fabricated as an anode material for SIBs, and carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) are chosen as binders to mix the anode materials to compare their battery performance. The anode composite with CMC as the binder demonstrates an improved initial coulombic efficiency of 75.6%, a higher specific capacity (366 mA h g−1 at a current density of 1 A g−1) and a better cycling stability (305 mA h g−1 after 300 cycles). The anode material composed of few-layer MoS2 anchored on low-cost nitrogen-doped AMCRs with CMC as the binder can be a competing candidate for large-scale SIB production.

Electrochemical water splitting is considered to be one of the most promising strategies to produce hydrogen to ease the energy crisis. In this study, we demonstrate a galvanic-replacement mediated synthesis of copper-nickel bimetallic nitrides on partially sacrificial nickel foams (CuxNi4−xN/NF) as the direct catalytic electrode for hydrogen evolution reaction (HER). The Ni foam serves as not only the cathodic electrode substrate, but also the only Ni precursor for the CuxNi4−xN catalyst, which can be galvanically replaced by Cu(I) ion. The obtained CuxNi4−xN/NF exhibits an excellent electrocatalytic performance towards the HER in both acidic and alkaline media with a very low overpotential of ∼110 mV at a current density of 100 mA cm−2 in the 0.5 M H2SO4 and 1 M KOH solutions. The electrode presents a good long-term working stability, particularly reflecting in more than 65 h of consistent galvanostatic electrolysis in 0.5 M H2SO4. The CuNi bimetallic nitrides are intrinsically metallic, allowing for an enhanced charge transport and an excellent electrical conductivity. Combining the experimental result and the theoretical calculation further reveals that the electrocatalytic active sites primarily originate from nickel species.

Hybrid carbon-coated transition metal oxides (TMOs@C) offer enhanced lithium storage capabilities, but the facile formation of TMOs@C nanocomposites remains a great challenge. Herein, we report a novel hierarchical hybrid nanostructure of carbon-coated CoFe2O4 twin elliptical frustums (CoFe2O4@C TEFs) via a quick one-pot refluxing reaction in ethylene glycol (EG) followed by an annealing treatment. When evaluated as an anode in lithium-ion batteries (LIBs), the resultant CoFe2O4@C TEF hybrids demonstrate good electrochemical performance with high reversible specific capacity, excellent rate capability and super-long life cycle. After 600 cycles at a current density of 500 mA g−1, the resultant TEFs still deliver a stable reversible discharge capacity of 875 mA h g−1. This work demonstrates the extensive potential of such simple synthetic methods towards various carbon coated transition metal oxide composites for energy conversion and storage devices.

In this work, we demonstrate a step-wise route to build a novel one-dimensional (1D) architecture formed by MoS2 nanosheets and amorphous carbon nanotubes (ACNTs). Being evaluated as an anode material for NIBs, the as-prepared MoS2@ACNT electrode is capable of exhibiting a remarkable reversible capacity of 461 mA h g−1 at a current density of 500 mA g−1 over 150 cycles. Moreover, the coulombic efficiency is almost up to 100% except for the initial few cycles during the whole cycling test. The smart electrode architecture and appropriate synergistic effect between MoS2 and ACNTs are probably responsible for the enhanced electrochemical performance.

Hierarchical hybrid nanostructures based on flexible graphene sheets and ternary transition metal oxides have attracted special attention as high-performance electrode materials for next-generation lithium-ion batteries (LIBs) yet their practical application is often beset with challenges. In this work, we report a hierarchical hybrid nanocomposite of reduced graphene oxide supported mesoporous Co3V2O8 nanoparticles (rGO@Co3V2O8 NPs) through a simple hydrothermal synthesis and post-calcination. This unique hybrid architecture when used as an anode in LIBs would effectively facilitate charge transfer, maintain structural integrity and accommodate the volume variation of the electrode materials during the repeated charge/discharge processes. As a result, the hybrid rGO@Co3V2O8 NPs manifest a very stable high reversible capacity of 1050 mA h g−1 over 200 cycles at a current density of 50 mA g−1 and excellent rate capability. Importantly, even when cycled at a higher current density of 200 mA g−1, a stable reversible capacity of 899 mA h g−1 and a remarkable cycling stability could also be achieved after 600 cycles. These results indicate the potential suitability of such mesoporous nanoparticles on graphene nanostructures for high-rate and long cycle life anode materials.

Hybrid nanosheet structures based on carbon coated metal oxides still attract promising interest as high-performance electrode materials for next-generation lithium-ion batteries (LIBs). In this study, we develop a simple one-pot solution method to synthesize large-scale flat Fe3O4 nanosheet hybrid structures coated with an amorphous carbon overlayer (denoted as Fe3O4@C NSs) followed by a thermal annealing treatment. It is found that the refluxing temperature plays an important role in adjusting the morphology of the Fe3O4@C hybrid. Increasing the temperature from 140 °C to 200 °C will lead to flower-like hybrid structures constructed by Fe3O4 nanoflakes gradually growing, rupturing, and finally evolving into flat and completely separate nanoflakes with large size at 200 °C. When evaluated as an anode material for LIBs, the hybrid Fe3O4@C NSs demonstrate a high reversible capacity of 1232 mA h g−1 over 120 cycles at a current density of 200 mA g−1, and remarkable rate capability.

Uniform SnO2 nanotubes with a mesoporous shell were successfully prepared by calcination of SnO2@polymeric nanotubes. The SnO2 nanotubes possess enhanced lithium storage performance compared with SnO2 hollow spheres and SnO2 nanoparticles owing to the unique structure of mesoporous shell, open ends and hollow interior.

Recently, tuning the normal ferroelectric performance of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-co-TrFE)) to either relaxor ferroelectric or anti-ferroelectric behavior by confining the relaxation of ferroelectric crystal domains physically or chemically has attracted considerable interest to achieve high discharged electric energy density (Ue) and low energy loss (Ul) for energy storage applications in high pulse capacitors. To improve the dielectric and energy storage properties as well as reduce the energy loss induced by the ferroelectric relaxation of P(VDF-co-TrFE), unsaturation containing P(VDF-co-TrFE) films were uniaxially stretched after crosslinking with peroxide in this work. P(VDF-co-TrFE) containing unsaturation was synthesized via controlled hydrogenation and dehydrochlorination of commercially available poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-co-CTFE)). The properties of the films obtained were characterized with differential scanning calorimetry (DSC), X-ray diffraction (XRD), dielectric constant and electric displacement–electric field (D–E) hysteresis loop measurements. Compared with the as-cast and as-crosslinked films, the stretched films exhibit a significantly enhanced dielectric constant, breakdown field (Eb > 500 MV m−1) and Ue but depressed energy loss. This could be attributed to the enhanced film quality, optimized crystalline properties, improved orientation uniformity of crystal domains as well as accelerated ferroelectric relaxation induced by the crosslinking and mechanical stretching. The best performance was achieved for the stretched film with a dielectric constant of 15 at 1 kHz, a relatively high Ue of 17.5 J cm−3 and a low energy loss of about 30% at 575 MV m−1.

One-dimensional heterogeneous crystalline TiO2–halloysite nanotubes with high visible-light photocatalytic activity have been successfully obtained by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb the TiO2 precursor and induce the growth of TiO2 nanocrystals on the support in situ. By simply adjusting the acidity of the TiO2 sol, crystalline TiO2 composite halloysite nanotubes with tunable crystalline phases of anatase or anatase/rutile mixed phases were achieved. The traditional thermal treatment for crystallite transformation was not required, thus an intact halloysite structure could be guaranteed. The as-obtained products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption–desorption, UV-vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The photocatalysis test results revealed that the obtained heterogeneous TiO2–halloysite showed enhanced visible-light photocatalytic activity for the degradation of rhodamine B and gentian violet compared with the pure halloysite nanotubes and Degussa-P25 owing to the heterogeneous TiO2 structure.