Porous g‐C₃N₄ and MXene Dual‐Confined FeOOH Quantum Dots for Superior Energy Storage in an Ionic Liquid

Abstract

Owing to their unique nanosize effect and surface effect, pseudocapacitive quantum dots (QDs) hold considerable potential for high‐efficiency supercapacitors (SCs). However, their pseudocapacitive behavior is exploited in aqueous electrolytes with narrow potential windows, thereby leading to a low energy density of the SCs. Here, a film electrode based on dual‐confined FeOOH QDs (FQDs) with superior pseudocapacitive behavior in a high‐voltage ionic liquid (IL) electrolyte is put forward. In such a film electrode, FQDs are steadily dual‐confined in a 2D heterogeneous nanospace supported by graphite carbon nitride (g‐C3N4) and Ti‐MXene (Ti3C2). Probing of potential‐driven ion accumulation elucidates that strong adsorption occurs between the IL cation and the electrode surface with abundant active sites, providing sufficient redox reaction of FQDs in the film electrode. Furthermore, porous g‐C3N4 and conductive Ti3C2 act as ion‐accessible channels and charge‐transfer pathways, respectively, endowing the FQDs‐based film electrode with favorable electrochemical kinetics in the IL electrolyte. A high‐voltage flexible SC (FSC) based on an ionogel electrolyte is fabricated, exhibiting a high energy density (77.12 mWh cm−3), a high power density, a remarkable rate capability, and long‐term durability. Such an FSC can also be charged by harvesting sustainable energy and can effectively power various wearable and portable electronics.

Turning Trash into Treasure: Additive Free MXene Sediment Inks for Screen‐Printed Micro‐Supercapacitors

“…[ 22–24 ] MXenes are typically obtained by selective removal of the A element (group 14 and 15, i.e., Al or Ga) from the MAX precursors. [ 25,26 ] Due to their exotic electrical, mechanical, thermal, optical properties and so forth, [ 27,28 ] MXenes, especially the most widely studied member Ti 3 C 2 T x (where T x is surface termination groups), have quickly attracted huge research attention in many areas covering electrochemical energy storage, [ 29–36 ] electromagnetic interference shielding, [ 37,38 ] catalysis, [ 39 ] sensing, [ 40 ] transparent conductive films, [ 41 ] with excellent performances. By delaminating multilayered Ti 3 C 2 T x (m‐Ti 3 C 2 T x ), colloidal solutions composed predominantly of monolayered nanosheets are obtained, which can be further employed for inkjet or extrusion printing.…”

Vertically Aligned Sn4+ Preintercalated Ti2CTX MXene Sphere with Enhanced Zn Ion Transportation and Superior Cycle Lifespan

“…Obviously, as observed in Figure 4c, the obtained self-discharge performances are superior to the reported MXene-based supercapacitors/batteries whose voltage and capacity decay in a very short time. [51][52][53][54][55][56] The battery-type anode (Zn metal) should be primarily responsible for the outstanding self-discharging performance. [51] When charging, Zn 2+ ions are reduced to Zn atoms instead of ions shuttle, which greatly prevents the accumulation behavior of cations on the anode and thus weakens the internal electrostatic field, differing from the ions shuttle of the intercalatedtype anode, as illustrated in Figure 4d.…”

Fabrication of TiO2/high‐crystalline g‐C3N4 composite with enhanced visible‐light photocatalytic performance for tetracycline degradation

“…1(a)], corresponding to in-plane structural packing motifs and the inter-planar stacking of the aromatic system. [20][21][22] Compared with BCN, HCCN [red line of Fig. 1(a)] possesses a similar pattern with higher angles and narrower peak [see the red line in Fig.…”