[1] ZHU L Q, WAN C J, GUO L Q et al. Artificial synapse network on inorganic proton conductor for neuromorphic systems[J]. Nature Communications(2014).

[2] KANEKO Y, NISHITANI Y, UEDA M. Ferroelectric artificial synapses for recognition of a multishaded image[J]. IEEE Transactions on Electron Devices(2014).

[3] HUANG M, SCHWACKE M, ONEN M et al. Electrochemical ionic synapses: progress and perspectives[J]. Advanced Materials(2023).

[4] FULLER E J, GABALY F E, LÉONARD F et al. Li-ion synaptic transistor for low power analog computing[J]. Advanced Materials(2017).

[5] MILEWSKA A, ŚWIERCZEK K, TOBOLA J et al. The nature of the nonmetal-metal transition in Li_xCoO₂ oxide[J]. Solid State Ionics(2014).

[6] LEE J, NIKAM R D, LIM S et al. Excellent synaptic behavior of lithium-based nano-ionic transistor based on optimal WO_2.7 stoichiometry with high ion diffusivity[J]. Nanotechnology(2020).

[7] YANG C, SHANG D, LIU N et al. All-solid-state synaptic transistor with ultralow conductance for neuromorphic computing[J]. Advanced Functional Materials(2018).

[8] LI Y, FULLER E J, SUGAR J D et al. Filament-free bulk resistive memory enables deterministic analogue switching[J]. Advanced Materials(2020).

[9] KIM S, TODOROV T, ONEN M et al. Metal-oxide based, CMOS-compatible ECRAM for deep learning accelerator[J]. IEEE International Electron Devices Meeting, San Francisco, 2019: 35, 1-35.

[10] VAN DE BURGT Y, LUBBERMAN E, FULLER E J et al. A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing[J]. Nature Materials(2017).

[11] MELIANAS A, QUILL T J, LECROY G et al. Temperature- resilient solid-state organic artificial synapses for neuromorphic computing[J]. Science Advances(2020).

[12] ONEN M, EMOND N, WANG B et al. Nanosecond protonic programmable resistors for analog deep learning[J]. Science(2022).

[13] KIREEV D, LIU S, JIN H et al. Metaplastic and energy-efficient biocompatible graphene artificial synaptic transistors for enhanced accuracy neuromorphic computing[J]. Nature Communications(2022).

[14] MELIANAS A, KANG M, VAHIDMOHAMMADI A et al. High-speed ionic synaptic memory based on 2D titanium carbide MXene[J]. Advanced Functional Materials(2022).

[15] JONAS F, SCHRADER L. Conductive modifications of polymers with polypyrroles and polythiophenes[J]. Synthetic Metals(1991).

[16] BOMBILE J H, JANIK M J, MILNER S T. Polaron formation mechanisms in conjugated polymers[J]. Physical Chemistry Chemical Physics(2017).

[17] MORIN F J. Oxides which show a metal-to-insulator transition at the neel temperature[J]. Physical Review Letters(1959).

[18] GOODENOUGH J B. The two components of the crystallographic transition in VO₂[J]. Journal of Solid State Chemistry(1971).

[19] LI G, XIE D, ZHONG H et al. Photo-induced non-volatile VO₂ phase transition for neuromorphic ultraviolet sensors[J]. Nature Communications(2022).

[20] GE C, LI G, ZHOU Q et al. Gating-induced reversible H_xVO₂ phase transformations for neuromorphic computing[J]. Nano Energy(2020).

[21] PARK J, OH C, SON J. Anisotropic ionic transport-controlled synaptic weight update by protonation in a VO₂ transistor[J]. Journal of Materials Chemistry C(2021).

[22] DENG X, WANG S, LIU Y et al. A flexible mott synaptic transistor for nociceptor simulation and neuromorphic computing[J]. Advanced Functional Materials(2021).

[23] OH C, KIM I, PARK J et al. Deep proton insertion assisted by oxygen vacancies for long-term memory in VO₂ synaptic transistor[J]. Advanced Electronic Materials(2021).

[24] WU Z, SHI P, XING R et al. Flexible mott synaptic transistor on polyimide substrate for physical neural networks[J]. Advanced Electronic Materials(2022).

[25] YANG J, MA C, GE C et al. Effects of line defects on the electronic and optical properties of strain-engineered WO₃ thin films[J]. Journal of Materials Chemistry C(2017).

[26] HJELM A, GRANQVIST C G, WILLS J M. Electronic structure and optical properties of WO₃, LiWO₃, NaWO₃, and HWO₃[J]. Physical Review B(1996).

[27] YAO X, KLYUKIN K, LU W et al. Protonic solid-state electrochemical synapse for physical neural networks[J]. Nature Communications(2020).

[28] YANG J, GE C, DU J et al. Artificial synapses emulated by an electrolyte-gated tungsten-oxide transistor[J]. Advanced Materials(2018).

[29] CUI J, AN F, QIAN J et al. CMOS-compatible electrochemical synaptic transistor arrays for deep learning accelerators[J]. Nature Electronics(2023).

[30] ONEN M, EMOND N, LI J et al. CMOS-compatible protonic programmable resistor based on phosphosilicate glass electrolyte for analog deep learning[J]. Nano Letters(2021).

[31] GOKMEN T, VLASOV Y. Acceleration of deep neural network training with resistive cross-point devices: design considerations[J]. Frontiers in Neuroscience(2016).

[32] GUO L Q, HAN H, ZHU L Q et al. Oxide neuromorphic transistors gated by polyvinyl alcohol solid electrolytes with ultralow power consumption[J]. ACS Applied Materials & Interfaces(2019).

[33] MOHANTY H N, TSURUOKA T, MOHANTY J R et al. Proton-gated synaptic transistors, based on an electron-beam patterned Nafion electrolyte[J]. ACS Applied Materials & Interfaces(2023).

[34] YU C, LI S, PAN Z et al. Gate-controlled neuromorphic functional transition in an electrochemical graphene transistor[J]. Nano Letters(2024).

[35] FERRARI A C, BASKO D M. Raman spectroscopy as a versatile tool for studying the properties of graphene[J]. Nature Nanotechnology(2013).

[36] MALARD L M, PIMENTA M A, DRESSELHAUS G et al. Raman spectroscopy in graphene[J]. Physics Reports(2009).

[37] ELIAS D C, NAIR R R, MOHIUDDIN T M G et al. Control of graphene’s properties by reversible hydrogenation: evidence for graphane[J]. Science(2009).

[38] BOUKHVALOV D W, KATSNELSON M I, LICHTENSTEIN A I. Hydrogen on graphene: electronic structure, total energy, structural distortions and magnetism from first-principles calculations[J]. Physical Review B(2008).

[39] HART J L, HANTANASIRISAKUL K, LANG A C et al. Control of MXenes’ electronic properties through termination and intercalation[J]. Nature Communications(2019).

[40] SHAKYA J, KANG M A, LI J et al. 2D MXene electrochemical transistors[J]. Nanoscale(2024).

[41] YANG C S, SHANG D S, LIU N et al. A synaptic transistor based on quasi-2D molybdenum oxide[J]. Advanced Materials(2017).

[42] CHENG H, WEN M, MA X et al. Hydrogen doped metal oxide semiconductors with exceptional and tunable localized surface plasmon resonances[J]. Journal of the American Chemical Society(2016).

[43] XIE L, ZHU Q, ZHANG G et al. Tunable hydrogen doping of metal oxide semiconductors with acid-metal treatment at ambient conditions[J]. Journal of the American Chemical Society(2020).

[44] KUMAR M N V R. A review of chitin and chitosan applications[J]. Reactive and Functional Polymers(2000).

[45] REN Z Y, ZHU L Q, YU F et al. Synaptic metaplasticity of protonic/electronic coupled oxide neuromorphic transistor[J]. Organic Electronics(2019).

[46] LI Y, HUANG Y J, CHEN X L et al. Multi-terminal pectin/chitosan hybrid electrolyte gated oxide neuromorphic transistor with multi-mode cognitive activities[J]. Frontiers of Physics(2024).

[47] LI Y, ZHANG C, ZHAO X et al. Ultrasensitive and degradable ultraflexible synaptic transistors based on natural pectin[J]. ACS Applied Electronic Materials(2022).

[48] HU W, JIANG J, XIE D et al. Transient security transistors self- supported on biodegradable natural-polymer membranes for brain- inspired neuromorphic applications[J]. Nanoscale(2018).

[49] LIU Y, FENG G, ZHU Q et al. Synaptic devices with sodium alginate ionic gel gating for global regulation[J]. Journal of Applied Physics(2024).

[50] HUANG K W, ZHU L, YING L Y et al. Artificial synaptic transistors based on konjac glucomannan for brain-inspired neuromorphic applications[J]. ACS Applied Electronic Materials(2024).

[51] KREUER K D. Proton conductivity: materials and applications[J]. Chemistry of Materials(1996).

[52] MAURITZ K A, MOORE R B. State of understanding of Nafion[J]. Chemical Reviews(2004).

[53] FENG C, HE P F. Moisture and thermal expansion properties and mechanism of interaction between ions of a Nafion-based membrane electrode assembly[J]. RSC Advances(2017).

[54] LARSSON O, SAID E, BERGGREN M et al. Insulator polarization mechanisms in polyelectrolyte-gated organic field-effect transistors[J]. Advanced Functional Materials(2009).

[55] ZHANG W, LI J, CHENG L et al. Synaptic transistor arrays based on PVA/lignin composite electrolyte films[J]. IEEE Transactions on Electron Devices(2023).

[56] LEE J, LIM S, KWAK M et al. Understanding of proton induced synaptic behaviors in three-terminal synapse device for neuromorphic systems[J]. Nanotechnology(2019).

[57] ZHANG L, LIU Z, YANG C et al. Conduction mechanism in graphene oxide membranes with varied water content: from proton hopping dominant to ion diffusion dominant[J]. ACS Nano(2022).

[58] NIKAM R D, LEE J, CHOI W et al. Ionic sieving through one-atom-thick 2D material enables analog nonvolatile memory for neuromorphic computing[J]. Small(2021).

[59] WAN C J, ZHU L Q, ZHOU J M et al. Memory and learning behaviors mimicked in nanogranular SiO₂-based proton conductor gated oxide-based synaptic transistors[J]. Nanoscale(2013).

[60] GUO L Q, WEN J, ZHU L Q et al. Humidity-dependent synaptic plasticity for proton gated oxide synaptic transistor[J]. IEEE Electron Device Letters(2017).

[61] MENG Y, GAO J, ZHAO Z et al. Review: recent progress in low-temperature proton-conducting ceramics[J]. Journal of Materials Science(2019).

[62] WU Z, SHI P, XING R et al. Quasi-two-dimensional α-molybdenum oxide thin film prepared by magnetron sputtering for neuromorphic computing[J]. RSC Advances(2022).

[63] LOZADA-HIDALGO M, HU S, MARSHALL O et al. Sieving hydrogen isotopes through two-dimensional crystals[J]. Science(2016).

[64] HU S, GOPINADHAN K, RAKOWSKI A et al. Transport of hydrogen isotopes through interlayer spacing in van der Waals crystals[J]. Nature Nanotechnology(2018).

[65] WAN C J, ZHU L Q, LIU Y H et al. Proton-conducting graphene oxide-coupled neuron transistors for brain-inspired cognitive systems[J]. Advanced Materials(2016).

[66] MOGG L, ZHANG S, HAO G P et al. Perfect proton selectivity in ion transport through two-dimensional crystals[J]. Nature Communications(2019).

[67] HU S, LOZADA-HIDALGO M, WANG F C et al. Proton transport through one-atom-thick crystals[J]. Nature(2014).