Single lithium-ion channel polymer binder for stabilizing sulfur cathodes

Lithium–sulfur batteries have great potential for high-performance energy-storage devices, yet the severe diffusion of soluble polysulfide to electrolyte greatly limits their practical applications. To address the above issues, herein we design and synthesize a novel polymer binder with single lithium-ion channels allowing fast lithium-ion transport while blocking the shuttle of unnecessary polysulfide anions. In situ UV–vis spectroscopy measurements reveal that the prepared polymer binder has effective immobilization to polysulfide intermediates. As expected, the resultant sulfur cathode achieves an excellent specific capacity of 1310 mAh g⁻¹ at 0.2 C, high Coulombic efficiency of 99.5% at 0.5 C after 100 cycles and stable cycling performance for 300 cycles at 1 C (1 C = 1675 mA g⁻¹). This study reports a new avenue to assemble a polymer binder with a single lithium-ion channel for solving the serious problem of energy attenuation of lithium–sulfur batteries.     

Enabling Mg metal anodes rechargeable in conventional electrolytes by fast ionic transport interphase

Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free. However, Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes, leading to irreversible plating/stripping behavior of Mg. Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions. In the artificial coating layer, Mg₂Sn alloy composites offer a channel for fast ion transport and insulating MgCl₂/SnCl₂ bestows the necessary potential gradient to prevent deposition on the surface. Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)₂/DME electrolyte are obtained. The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm⁻². This finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.     

Encapsulating metal organic framework into hollow mesoporous carbon sphere as efficient oxygen bifunctional electrocatalyst

Applying metal organic frameworks (MOFs) in electrochemical systems is a currently emerging field owing to the rich metal nodes and highly specific surface area of MOFs. However, the problems for MOFs that need to be solved urgently are poor electrical conductivity and low ion transport. Here we present a facile in situ growth method for the rational synthesis of MOFs@hollow mesoporous carbon spheres (HMCS) yolk–shell-structured hybrid material for the first time. The size of the encapsulated Zeolitic Imidazolate Framework-67 (ZIF-67) is well controlled to 100 nm due to the spatial confinement effect of HMCS, and the electrical conductivity of ZIF-67 is also increased significantly. The ZIF@HMCS-25% hybrid material obtained exhibits a highly efficient oxygen reduction reaction activity with 0.823 V (vs. reversible hydrogen electrode) half-wave potential and an even higher kinetic current density (J_K = 13.8 mA cm⁻²) than commercial Pt/C. ZIF@HMCS-25% also displays excellent oxygen evolution reaction performance and the overpotential of ZIF@HMCS-25% at 10 mA cm⁻² is 407 mV. In addition, ZIF@HMCS-25% is further employed as an air electrode for a rechargeable Zn–air battery, exhibiting a high power density (120.2 mW cm⁻² at 171.4 mA cm⁻²) and long-term charge/discharge stability (80 h at 5 mA cm⁻²). This MOFs@HMCS yolk–shell design provides a versatile method for the application of MOFs as electrocatalysts directly.     

Influence of Altered Hormonal Status on Platelet 5-HT and MAO-B Activity in Cigarette Smokers

The present study was designed to understand the cigarette smoking-induced alterations in hormones and the resulting changes in platelet serotonin (5-hydroxytryptamine, 5-HT) and monoamine oxidase (MAO-B) activity in chronic smokers. Human male volunteers aged 35 ± 8 years, were divided into two groups, namely controls and smokers (12 ± 2 cigarettes per day for 7–10 years). Results showed that cigarette smoking significantly (p < 0.05) elevated plasma triiodothyronine (T₃), cortisol and testosterone levels with significant (p < 0.05) reduction in plasma tryptophan and thyroxin (T₄). Moreover, smokers showed reduced platelet 5-HT levels and MAO-B activity. In smokers, plasma cortisol was negatively correlated with tryptophan (r = −0.386), platelet MAO-B (r = −0.264), and 5-HT (r = −0.671), and positively correlated with testosterone (r = 0.428). However, testosterone was negatively correlated with platelet MAO-B (r = −0.315), and 5-HT (r = −.419) in smokers. Further, smokers plasma T₃ levels were negatively correlated with platelet MAO-B (r = −0.398), and 5-HT (r = −0.541), whereas T₄ levels were positively correlated with platelet MAO-B (r = 0.369), and 5-HT (r = 0.454). In conclusion, our study showed that altered testosterone and cortisol levels may aggravate behavior, mood disturbances and symptoms of depression by decreasing platelet 5-HT and MAO-B activity in smokers.     

Graphdiyne-based metal atomic catalysts for synthesizing ammonia

Development of novel catalysts for nitrogen reduction at ambient pressures and temperatures with ultrahigh ammonia (NH₃) yield and selectivity is challenging. In this work, an atomic catalyst with separated Pd atoms on graphdiyne (Pd-GDY) was synthesized, which shows fascinating electrocatalytic properties for nitrogen reduction. The catalyst has the highest average NH₃ yield of 4.45 ± 0.30 mg_NH3 mg_Pd⁻¹ h⁻¹, almost tens of orders larger than for previously reported catalysts, and 100% reaction selectivity in neutral media. Pd-GDY exhibits almost no decreases in NH₃ yield and Faradaic efficiency. Density functional theory calculations show that the reaction pathway prefers to perform at the (Pd, C1, C2) active area because of the strongly coupled (Pd, C1, C2), which elevates the selectivity via enhanced electron transfer. By adjusting the p–d coupling accurately, reduction of self-activated nitrogen is promoted by anchoring atom selection, and side effects are minimized.     

Large-scale multiferroic complex oxide epitaxy with magnetically switched polarization enabled by solution processing

Complex oxides with tunable structures have many fascinating properties, though high-quality complex oxide epitaxy with precisely controlled composition is still out of reach. Here we have successfully developed solution-based single-crystalline epitaxy for multiferroic (1-x)BiTi_(1-y)/2Fe_yMg_(1-y)/2O₃–(x)CaTiO₃ (BTFM–CTO) solid solution in large area, confirming its ferroelectricity at the atomic scale with strong spontaneous polarization. Careful compositional tuning leads to a bulk magnetization of 0.07 ± 0.035 μ_B/Fe at room temperature, enabling magnetically induced polarization switching exhibiting a large magnetoelectric coefficient of 2.7–3.0 × 10⁻⁷ s/m. This work demonstrates the great potential of solution processing in large-scale complex oxide epitaxy and establishes novel room-temperature magnetoelectric coupling in epitaxial BTFM–CTO film, making it possible to explore a much wider space of composition, phase, and structure that can be easily scaled up for industrial applications.     

Human activities aggravate nitrogen-deposition pollution to inland water over China

In the past three decades, China has built more than 87 000 dams with a storage capacity of ≈6560 km³ and the total surface area of inland water has increased by 6672 km². Leaching of N from fertilized soils to rivers is the main source of N pollution in China, but the exposure of a growing inland water area to direct atmospheric N deposition and N leaching caused by N deposition on the terrestrial ecosystem, together with increased N deposition and decreased N flow, also tends to raise N concentrations in most inland waters. The contribution of this previously ignored source of  N deposition to freshwaters is estimated in this study, as well as mitigation strategies. The results show that the annual amounts of N depositions ranged from 4.9 to 16.6 kg · ha⁻¹ · yr⁻¹ in the 1990s to exceeding 20 kg · ha⁻¹ · yr⁻¹ in the 2010s over most of regions in China, so the total mass of ΔN (the net contribution of N deposition to the increase in N concentration) for lakes, rivers and reservoirs change from 122.26 Gg N · yr⁻¹ in the 1990s to 237.75 Gg N · yr⁻¹ in the 2010s. It is suggested that reducing the N deposition from various sources, shortening the water-retention time in dams and decreasing the degree of regulation for rivers are three main measures for preventing a continuous increase in the N-deposition pollution to inland water in China.     

Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration

Resolving regional carbon budgets is critical for informing land-based mitigation policy. For nine regions covering nearly the whole globe, we collected inventory estimates of carbon-stock changes complemented by satellite estimates of biomass changes where inventory data are missing. The net land–atmospheric carbon exchange (NEE) was calculated by taking the sum of the carbon-stock change and lateral carbon fluxes from crop and wood trade, and riverine-carbon export to the ocean. Summing up NEE from all regions, we obtained a global ‘bottom-up’ NEE for net land anthropogenic CO₂ uptake of –2.2 ± 0.6 PgC yr⁻¹ consistent with the independent top-down NEE from the global atmospheric carbon budget during 2000–2009. This estimate is so far the most comprehensive global bottom-up carbon budget accounting, which set up an important milestone for global carbon-cycle studies. By decomposing NEE into component fluxes, we found that global soil heterotrophic respiration amounts to a source of CO₂ of 39 PgC yr⁻¹ with an interquartile of 33–46 PgC yr⁻¹—a much smaller portion of net primary productivity than previously reported.     

A highly alkaline-stable metal oxide@metal–organic framework composite for high-performance electrochemical energy storage

Most metal–organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to alkaline aqueous solutions, thus precluding their use as potential electrode materials for electrochemical energy storage devices. Here, we present the design and synthesis of a highly alkaline-stable metal oxide@MOF composite, Co₃O₄ nanocube@Co-MOF (Co₃O₄@Co-MOF), via a controllable and facile one-pot hydrothermal method under highly alkaline conditions. The obtained composite possesses exceptional alkaline stability, retaining its original structure in 3.0 M KOH for at least 15 days. Benefitting from the exceptional alkaline stability, unique structure, and larger surface area, the Co₃O₄@Co-MOF composite shows a specific capacitance as high as 1020 F g⁻¹ at 0.5 A  g⁻¹ and a high cycling stability with only 3.3% decay after 5000 cycles at 5 A g⁻¹. The as-constructed solid-state flexible device exhibits a maximum energy density of 21.6 mWh cm⁻³.     

Gold coated optical fibers as three-dimensional electrodes for microfluidic enzymatic biofuel cells: Toward geometrically enhanced performance

For the first time, we report on the preliminary evaluation of gold coated optical fibers (GCOFs) as three-dimensional (3D) electrodes for a membraneless glucose/O₂ enzymatic biofuel cell. Two off-the-shelf 125 μm diameter GCOFs were integrated into a 3D microfluidic chip fabricated via rapid prototyping. Using soluble enzymes and a 10 mM glucose solution flowing at an average velocity of 16 mm s⁻¹ along 3 mm long GCOFs, the maximum power density reached 30.0 ± 0.1 μW cm⁻² at a current density of 160.6 ± 0.3 μA cm⁻². Bundles composed of multiple GCOFs could further enhance these first results while serving as substrates for enzyme immobilization.     

Exposed facet-controlled N2 electroreduction on distinct Pt3Fe nanostructures of nanocubes,nanorods and nanowires

Understanding the correlation between exposed surfaces and performances of controlled nanocatalysts can aid effective strategies to enhance electrocatalysis, but this is as yet unexplored for the nitrogen reduction reaction (NRR). Here, we first report controlled synthesis of well-defined Pt₃Fe nanocrystals with tunable morphologies (nanocube, nanorod and nanowire) as ideal model electrocatalysts for investigating the NRR on different exposed facets. The detailed electrocatalytic studies reveal that the Pt₃Fe nanocrystals exhibit shape-dependent NRR electrocatalysis. The optimized Pt₃Fe nanowires bounded with high-index facets exhibit excellent selectivity (no N₂H₄ is detected), high activity with NH₃ yield of 18.3 μg h⁻¹ mg⁻¹_cat (0.52 μg h⁻¹ cm⁻²_ECSA; ECSA: electrochemical active surface area) and Faraday efficiency of 7.3% at −0.05 V versus reversible hydrogen electrode, outperforming the {200} facet-enclosed Pt₃Fe nanocubes and {111} facet-enclosed Pt₃Fe nanorods. They also show good stability with negligible activity change after five cycles. Density functional theory calculations reveal that, with high-indexed facet engineering, the Fe-3d band is an efficient d-d coupling correlation center for boosting the Pt 5d-electronic exchange and transfer activities towards the NRR.     

Experiments on Cu-isotope fractionation between chlorine-bearing fluid and silicate magma: implications for fluid exsolution and porphyry Cu deposits

Hydrothermal fluid is essential for transporting metals in the crust and mantle. To explore the potential of Cu isotopes as a tracer of hydrothermal-fluid activity, Cu-isotope fractionation factors between Cl-bearing aqueous fluids and silicate magmas (andesite, dacite, rhyolite dacite, rhyolite and haplogranite) were experimentally calibrated. Fluids containing 1.75–14 wt.% Cl were mixed together with rock powders in Au₉₅Cu₅ alloy capsules, which were equilibrated in cold-seal pressure vessels for 5–13 days at 800–850°C and 2 kbar. The elemental and Cu-isotopic compositions of the recovered aqueous fluid and solid phases were analyzed by (LA-) ICP–MS and multi-collector inductively coupled plasma mass spectrometry, respectively. Our experimental results show that the fluid phases are consistently enriched in heavy Cu isotope (⁶⁵Cu) relative to the coexisting silicates. The Cu-isotope fractionation factor (Δ⁶⁵Cu_FLUID-MELT) ranges from 0.08 ± 0.01‰ to 0.69 ± 0.02‰. The experimental results show that the Cu-isotopic fractionation factors between aqueous fluids and silicates strongly depend on the Cu speciation in the fluids (e.g. CuCl(H₂O), CuCl₂^– and CuCl₃²⁻) and silicate melts (CuO_1/2), suggesting that the exsolved fluids may have higher δ⁶⁵Cu than the residual magmas. Our results suggest the elevated δ⁶⁵Cu values in Cu-enriched rocks could be produced by addition of aqueous fluids exsolved from magmas. Together with previous studies on Cu isotopes in the brine and vapor phases of porphyry deposits, our results are helpful for better understanding Cu-mineralization processes.     

Ferrimagnetic mPEG-b-PHEP copolymer micelles loaded with iron oxide nanocubes and emodin for enhanced magnetic hyperthermia–chemotherapy

As a non-invasive therapeutic method without penetration-depth limitation, magnetic hyperthermia therapy (MHT) under alternating magnetic field (AMF) is a clinically promising thermal therapy. However, the poor heating conversion efficiency and lack of stimulus–response obstruct the clinical application of magnetofluid-mediated MHT. Here, we develop a ferrimagnetic polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane) (mPEG-b-PHEP) copolymer micelle loaded with hydrophobic iron oxide nanocubes and emodin (denoted as EMM). Besides an enhanced magnetic resonance (MR) contrast ability (r₂ = 271 mM⁻¹ s⁻¹) due to the high magnetization, the specific absorption rate (2518 W/g at 35 kA/m) and intrinsic loss power (6.5 nHm²/kg) of EMM are dozens of times higher than the clinically available iron oxide nanoagents (Feridex and Resovist), indicating the high heating conversion efficiency. Furthermore, this composite micelle with a flowable core exhibits a rapid response to magnetic hyperthermia, leading to an AMF-activated supersensitive drug release. With the high magnetic response, thermal sensitivity and magnetic targeting, this supersensitive ferrimagnetic nanocomposite realizes an above 70% tumor cell killing effect at an extremely low dosage (10 μg Fe/mL), and the tumors on mice are completely eliminated after the combined MHT–chemotherapy.     

Serum Testosterone, 17β-Estradiol and PSA Levels in Subjects with Prostate Disorders

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of death as a result of cancer in men in the US and other parts of the world. There are conflicting reports on the serum levels of testosterone and 17β-estradiol (E₂) in benign prostatic hyperplasia (BPH) and prostate cancer. This study was designed to evaluate the serum concentrations of these hormones in patients with these disorders. Serum levels of prostate specific antigen (PSA), total testosterone and estradiol were determined in 228 subjects comprising of 116 subjects with BPH, 62 subjects with prostate cancer (CaP) and 50 age-matched apparently healthy controls, using ELISA methods. PSA levels were significantly elevated (p < 0.05) in BPH subjects than controls, while there was no significant difference (p > 0.05) in testosterone and estradiol levels of these subjects. PSA and estradiol levels were significantly higher (p < 0.05) in CaP subjects than in controls, while there was no observed significant difference (p > 0.05) in testosterone levels. CaP subjects had significantly raised PSA, testosterone, and estradiol levels than BPH subjects. The mean molar ratio of testosterone: E₂ was lowest among CaP patients (134:1) and highest among controls (166:1). Significant positive correlation between PSA and 17β-estradiol was observed in prostate disorders (BPH and CaP patients: r = 0.347; p = 0.000). Significant negative correlations between testosterone and PSA were also observed among BPH patients (r = −0.221, p = 0.049) and control subjects (r = −0.490, p = 0.000). No significant correlation existed between testosterone and PSA in CaP patients (r = 0.051, p = 0.693). Correlations between age and estradiol in both BPH and CaP were not significant (p > 0.05). This study has shown that, there was a significant increase in serum estradiol in CaP subjects, while the testosterone levels in both BPH and CaP subjects were not different from those of controls.     

Prioritizing natural-selection signals from the deep-sequencing genomic data suggests multi-variant adaptation in Tibetan highlanders

Human genetic adaptation to high altitudes (>2500 m) has been extensively studied over the last few years, but few functional adaptive genetic variants have been identified, largely owing to the lack of deep-genome sequencing data available to previous studies. Here, we build a list of putative adaptive variants, including 63 missense, 7 loss-of-function, 1,298 evolutionarily conserved variants and 509 expression quantitative traits loci. Notably, the top signal of selection is located in TMEM247, a transmembrane protein-coding gene. The Tibetan version of TMEM247 harbors one high-frequency (76.3%) missense variant, rs116983452 (c.248C > T; p.Ala83Val), with the T allele derived from archaic ancestry and carried by >94% of Tibetans but absent or in low frequencies (<3%) in non-Tibetan populations. The rs116983452-T is strongly and positively correlated with altitude and significantly associated with reduced hemoglobin concentration (p = 5.78 × 10⁻⁵), red blood cell count (p = 5.72 × 10⁻⁷) and hematocrit (p = 2.57 × 10⁻⁶). In particular, TMEM247-rs116983452 shows greater effect size and better predicts the phenotypic outcome than any EPAS1 variants in association with adaptive traits in Tibetans. Modeling the interaction between TMEM247-rs116983452 and EPAS1 variants indicates weak but statistically significant epistatic effects. Our results support that multiple variants may jointly deliver the fitness of the Tibetans on the plateau, where a complex model is needed to elucidate the adaptive evolution mechanism.     

Ultra-small hollow ternary alloy nanoparticles for efficient hydrogen evolution reaction

Hollow nanoparticles with large specific surface area and high atom utilization are promising catalysts for the hydrogen evolution reaction (HER). We describe herein the design and synthesis of a series of ultra-small hollow ternary alloy nanostructures using a simple one-pot strategy. The same technique was demonstrated for hollow PtNiCu nanoparticles, hollow PtCoCu nanoparticles and hollow CuNiCo nanoparticles. During synthesis, the displacement reaction and oxidative etching played important roles in the formation of hollow structures. Moreover, our hollow PtNiCu and PtCoCu nanoparticles were single crystalline, with an average diameter of 5 nm. Impressively, ultra-small hollow PtNiCu nanoparticles, containing only 10% Pt, exhibited greater electrocatalytic HER activity and stability than a commercial Pt/C catalyst. The overpotential of hollow PtNiCu nanoparticles at 10 mA cm⁻² was 28 mV versus reversible hydrogen electrode (RHE). The mass activity was 4.54 A mg_Pt⁻¹ at −70 mV versus RHE, which is 5.62-fold greater than that of a commercial Pt/C system (0.81 A mg_Pt⁻¹). Through analyses of bonding and antibonding orbital filling, density functional theory calculations demonstrated that the bonding strength of different metals to the hydrogen intermediate (H^*) was in the order of Pt > Co > Ni > Cu. The excellent HER performance of our hollow PtNiCu nanoparticles derives from moderately synergistic interactions between the three metals and H^*. This work demonstrates a new strategy for the design of low-cost and high-activity HER catalysts.     

Cell-like-carbon-micro-spheres for robust potassium anode

Large-scale low-cost synthesis methods for potassium ion battery (PIB) anodes with long cycle life and high capacity have remained challenging. Here, inspired by the structure of a biological cell, biomimetic carbon cells (BCCs) were synthesized and used as PIB anodes. The protruding carbon nanotubes across the BCC wall mimicked the ion-transporting channels present in the cell membrane, and enhanced the rate performance of PIBs. In addition, the robust carbon shell of the BCC could protect its overall structure, and the open space inside the BCC could accommodate the volume changes caused by K⁺ insertion, which greatly improved the stability of PIBs. For the first time, a stable solid electrolyte interphase layer is formed on the surface of amorphous carbon. Collectively, the unique structural characteristics of the BCCs resulted in PIBs that showed a high reversible capacity (302 mAh g⁻¹ at 100 mA g⁻¹ and 248 mAh g⁻¹ at 500 mA g⁻¹), excellent cycle stability (reversible capacity of 226 mAh g⁻¹ after 2100 cycles and a continuous running time of more than 15 months at a current density of 100 mA g⁻¹), and an excellent rate performance (160 mAh g⁻¹ at 1 A g⁻¹). This study represents a new strategy for boosting battery performance, and could pave the way for the next generation of battery-powered applications.     

Integrated ‘all-in-one’ strategy to stabilize zinc anodes for high-performance zinc-ion batteries

Many optimization strategies have been employed to stabilize zinc anodes of zinc-ion batteries (ZIBs). Although these commonly used strategies can improve anode performance, they simultaneously induce specific issues. In this study, through the combination of structural design, interface modification, and electrolyte optimization, an ‘all-in-one’ (AIO) electrode was developed. Compared to the three-dimensional (3D) anode in routine liquid electrolytes, the new AIO electrode can greatly suppress gas evolution and the occurrence of side reactions induced by active water molecules, while retaining the merits of a 3D anode. Moreover, the integrated AIO strategy achieves a sufficient electrode/electrolyte interface contact area, so that the electrode can promote electron/ion transfer, and ensure a fast and complete redox reaction. As a result, it achieves excellent shelving-restoring ability (60 hours, four times) and 1200 cycles of long-term stability without apparent polarization. When paired with two common cathode materials used in ZIBs (α-MnO₂ and NH₄V₄O₁₀), full batteries with the AIO electrode demonstrate high capacity and good stability. The strategy of the ‘all-in-one’ architectural design is enlightened to solve the issues of zinc anodes in advanced Zn-based batteries.     

Unprecedented and highly stable lithium storage capacity of (001) faceted nanosheet-constructed hierarchically porous TiO2/rGO hybrid architecture for high-performance Li-ion batteries

Active crystal facets can generate special properties for various applications. Herein, we report a (001) faceted nanosheet-constructed hierarchically porous TiO₂/rGO hybrid architecture with unprecedented and highly stable lithium storage performance. Density functional theory calculations show that the (001) faceted TiO₂ nanosheets enable enhanced reaction kinetics by reinforcing their contact with the electrolyte and shortening the path length of Li⁺ diffusion and insertion-extraction. The reduced graphene oxide (rGO) nanosheets in this TiO₂/rGO hybrid largely improve charge transport, while the porous hierarchy at different length scales favors continuous electrolyte permeation and accommodates volume change. This hierarchically porous TiO₂/rGO hybrid anode material demonstrates an excellent reversible capacity of 250 mAh g^–1 at 1 C (1 C = 335 mA g^–1) at a voltage window of 1.0–3.0 V. Even after 1000 cycles at 5 C and 500 cycles at 10 C, the anode retains exceptional and stable capacities of 176 and 160 mAh g^–1, respectively. Moreover, the formed Li₂Ti₂O₄ nanodots facilitate reversed Li⁺ insertion-extraction during the cycling process. The above results indicate the best performance of TiO₂-based materials as anodes for lithium-ion batteries reported in the literature.     

Charmonium and charmoniumlike states at the BESIII experiment

Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 5 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of the M1 transition ψ(2S) → γη_c(2S) and the discovery of the ψ₂(3823) state; and report on studies of charmoniumlike states, including the discoveries of the Z_c(3900) and Z_c(4020) tetraquark candidates, the resolution of the fine structure of the Y(4260) state, the discovery of the new production process e⁺e⁻ → γX(3872) and the uncovering of strong evidence for the commonality among the X(3872), Y(4260) and Z_c(3900) states. The prospects for further research at BESIII and proposed future facilities are also presented.