Dynamic Electronic and Ionic Transport Actuated by Cobalt-Doped MoSe2 /rGO for Superior Potassium-Ion Batteries

Molybdenum selenium (MoSe2 ) has tremendous potential in potassium-ion batteries (PIBs) due to its large interlayer distance, favorable bandgap, and high theoretical specific capacity. However, the poor conductivity and large K+ insertion/extraction in MoSe2 inevitably leads to sluggish reaction kinetics and poor structural stability. Herein, Coinduced engineering is employed to illuminate high-conductivity electron pathway and mobile ion diffusion of MoSe2 nanosheets anchored on reduced graphene oxide substrate (Co-MoSe2 /rGO). Benefiting from the activated electronic conductivity and ion diffusion kinetics, and an expanded interlayer spacing resulting from Co doping, combined with the interface coupling with highly conductive reduced graphene oxide (rGO) substrate through Mo-C bonding, the Co-MoSe2 /rGO anode demonstrates remarkable reversible capacity, superior rate capability, and stable long-term cyclability for potassium storage, as well as superior energy density and high power density for potassium-ion capacitors. Systematic performance measurement, dynamic analysis, in-situ/ex-situ measurements, and density functional theory (DFT) calculations elucidate the performance-enhancing mechanism of Co-MoSe2 /rGO in view of the electronic and ionic transport kinetics. This work offers deep atomic insights into the fundamental factors of electrodes for potassium-ion batteries/capacitors with superior electrochemical performance.

Realizing Ultrahigh Transconductance in Organic Electrochemical Transistor by Co-Doping PEDOT:PSS with Ionic Liquid and Dodecylbenzenesulfonate

Organic electrochemical transistors (OECTs), especially the ones with high transconductance, are highly promising in sensitive detection of chemical and biological species. However, it is still a great challenge to design and fabricate OECTs with very high transconductance. Herein, an OECT with ultrahigh transconductance is reported by introducing ionic liquid and dodecylbenzenesulfonate (DBSA) simultaneously in poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) as the semiconductive channel. Compared with the OECT based on pristine PEDOT:PSS, the OECT based on co-doped PEDOT:PSS demonstrates a significant enhancement of transconductance from 1.85 to 22.7 mS, because of the increase in volumetric capacitance and conductivity. The enhanced transconductance is attributed to the DBSA-facilitated phase separation between the ionic liquid and PEDOT:PSS, which helps to form conductive domains of ionic liquid in PEDOT:PSS matrix, and the partial dispersion of ionic liquid in the PEDOT:PSS phase. Furthermore, by using the interdigitated electrodes as the source and drain electrodes, an ultrahigh transconductance of 180 mS is obtained, which is superior to that of the state-of-the-art OECTs. Because of the ultrahigh transconductance, the obtained OECT demonstrates sensitive detection of hydrogen peroxide and glucose, making it promising in clinical diagnosis, health monitoring, and environmental surveillance.