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An N-doped graphene aerogel (NGA) is used as a reactive container for growing MnO2 nanoparticles via a soaking–hydrothermal strategy. MnO2 nanoparticles pile up on the surface of reduced graphene oxide sheets with crosslinked structures serving as electrical conductors. Importantly, the NGA generates extra capacitance during the electrochemical process, which accomplishes a satisfactory compensation in the physical–chemical properties of MnO2. As a cathodic electrode for Zn-ion batteries, the MnO2/NGA exhibits a specific capacity of 275.8 mA h g−1 and pre-eminent cycling stability with a retention of 93.6% at 3 A g−1 after 1000 cycles. Meanwhile, the proposed electrode also shows a relatively high specific capacitance of 341 F g−1 for a supercapacitor in 1 M Na2SO4. Meanwhile, the long-term cycling stability shows only a slight decrease by 5.1% of the initial capacitance after 5000 continuous cycles at 3 A g−1, which indicates its superior electrochemical stability. Additionally, the assembled asymmetric supercapacitor also shows good electrochemical performance. This work highlights the extensive function of an N-doped graphene aerogel as a promising substrate for enhancing the electrochemical performance of MnO2, which opens the gate for wide potential applications of graphene aerogel composites emphasizing their complementary effects. [ABSTRACT FROM AUTHOR]

Aqueous ammonium-ion batteries have attracted more attentions. Electrodeposited manganese oxide (MnO x) electrodes stand out electrochemical behaviors for storing NH 4 +. However, the unsatisfied conductivity and dissolution of MnO x impede electrochemical properties of MnO x for applying in ammonium-ion batteries. In this work, electrochemical coverage of reduced graphene oxide (rGO) layers on MnO x was carried out to improve the properties of MnO x as a positive electrode of ammonium-ion batteries. The improvements are attributed to three functions of rGO additives to engage as conductive layers (fast electron transportation), blocking layers (inhibition of Mn2+ diffusion) and capacitive behaviors (adsorption of Mn2+ and NO x −), which makes sure the excellent rate capability (109 mAh g−1 at 5 A g−1) and cycling stability (92.6% after 1000 cycles) of rGO 60 /MnO x. In addition, we also studied the redox of NH 4 + on rGO layers to investigate the stability of electrolyte, and the redox of NH 4 + on rGO layers is highly reversible and low active, which implies that the rGO is suitable to be a functionalized component for improving the properties of MnO x to apply in ammonium-ion batteries. This work provides a new thought to design electrodes with comprehensive strategies for ammonium-ion batteries. Tight and incomplete coverage of reduced graphene oxide (rGO) layers on MnO x was adopted to improve the performance of MnO x for applying MnO x in ammonium-ion batteries, which aims to enhance the conductivity of MnO x -based electrode and decrease the amount of Mn2+ and NO x − diffusing from the surface of electrode to bulk electrolyte. [Display omitted] • Reduced graphene oxide cover on the surface of MnO x to improve the performance of MnO x for ammonium-ion batteries. • Reduced graphene oxide as blocking layers to inhibit the diffusion of Mn2+ and NO x − from the surface of MnO x to electrolyte. • Investigating the electrochemical effects of reduced graphene oxide layers on NH 4 + in electrolyte. [ABSTRACT FROM AUTHOR]

The paper presents a novel strategy for the fabrication of sandwich-like N, S co-doped graphene aerogels using π-π and H-bonding interactions between 2, 5-Dimercapto-1, 3, 4-thiadiazole (DMTD) and GO via hydrothermal method. The synergistic effect between N and S atoms plays key role to improve the supercapacitor performance of the fabricated graphene aerogel material. • π-conjugated DMTD molecules are used as dopant precursors and pillared agents for the fabrication of NSGA. • NSGA delivers a high gravimetric specific capacitance of 321 F g−1 at a current density of 1 A g−1. • The π-conjugated and H-bonding interactions improve the accessible surface area of NSGA. • The synergistic effect of N andS and enhancement of surface area are the main reason in promoting the SC performance. Rational constructing carbon electrode materials with heteroatoms (eg. N, S, B, F) and high surface area is essencial to the appealing performance of supercapacitor (SC). Here we present a novel fabrication strategy for sandwich-like N, S co-doped three-dimensional (3D) porous graphene aerogels (NSGAs) via one-pot hydrothermal method for high performance SCs materials. The unique advantage of the proposed synthesis strategy is the applications of 2, 5-Dimercapto-1, 3, 4-thiadiazole (DMTD) as bifunctional pillared agents and efficient dopant precursors. The planar DMTD molecules have shown strong supramolecular π-π and H-bonding interactions with graphene oxide (GO), thus avoiding the restacking of graphene sheets and enhancing the doping efficiency and amount of S atoms, which are beneficial to the SC performance of NSGA. The synthesized NSGA samples exhibit the atomic content of S up to 2.39 at.% with surface area at 366.0 m2 g−1, and display a maximum energy density of 10.52 W h kg−1 for assembled symmetric supercapacitor. The relatively high tandem device performance with a remarkable current response, even at 2000 mV s−1, reaches the top level for graphene-based SC system. The proposed simple fabrication strategy and attracting performance of NSGA material shed light on the potential practical applications of graphene-based material as SCs, and the observed structure-function relations also provides physical-chemical insight into the function principle of heteroatom doped graphene in SCs. [ABSTRACT FROM AUTHOR]

The novelty of this paper is that we use 5-mercapto-3-phenyl-1,3,4-thiadiazole-2(3H) thione potassium salt (BII) as pillaring agent and dopant to synthesize 3D sulfur and nitrogen co-doped graphene aerogel (SNGA) as supercapacitor electrode materials. It is noteworthy that BII is a vertical bicyclic molecule with a special head-to-head non-planar structure effectively inhibiting the close stacking of graphene sheets during the self-assembly process. Therefore, SNGA4 synthesized under optimal condition obtains a larger specific surface area (410.2 m2 g−1). At the same time, BII with rich sulfur and nitrogen promote the doping amount of sulfur atoms at 3.71 at.% via the supramolecular interactions (π-π interaction and hydrogen bonding). Furthermore, this work gives us a deeper understanding of how to choose pillaring agents and dopants in the fabrication of high-performance graphene-based. [Display omitted] • A vertical bicyclic BII molecule are used as pillaring agent and dopant for 3D sulfur and nitrogen co-doped graphene aerogel (SNGA). • The π-π interaction and H-bonding between BII and GO promote the doping of sulfur and nitrogen atoms of SNGA. • SNGA shows a high specific capacitance of 399 F g−1 at a current density of 1 A g−1. • The head-to-head vertical non-planar structure gives the BII a more significant effect in preventing graphene stacking. The two-dimensional (2D) graphene sheets can be self-assembled into three-dimensional (3D) graphene aerogels by a typical hydrothermal route to improve the supercapacitor performance in recent years. The novelty of this paper is that we use 5-mercapto-3-phenyl-1,3,4-thiadiazole-2(3H) thione potassium salt (BII) as pillaring agent and dopant to synthesize 3D sulfur and nitrogen co-doped graphene aerogel (SNGA) as supercapacitor electrode materials. It is noteworthy that BII is a vertical bicyclic molecule with a special head-to-head non-planar structure effectively inhibiting the close stacking of graphene sheets during the self-assembly process. Therefore, SNGA4 synthesized under optimal condition obtains a larger specific surface area (410.2 m2 g−1). At the same time, BII with rich sulfur and nitrogen promote the doping amount of sulfur atoms at 3.71 at.% via the supramolecular interactions (π-π interaction and hydrogen bonding). In the three-electrode configuration, the capacitance reached 399F g−1 (current density is 1 A g−1), and the energy density gained 11.36 Wh kg−1 in the assembled supercapacitor system. These results indicate the great potential of SNGA4 as an electrode material for supercapacitors. Furthermore, this work gives us a deeper understanding of how to choose pillaring agents and dopants in the fabrication of high-performance graphene-based supercapacitor electrodes. [ABSTRACT FROM AUTHOR]