Harvesting Biomass-Based Ni–N Doped Carbonaceous Materials with High Capacitance by Fast Pyrolysis of Ni Enriched Spent Wetland Biomass

Abstract

In this study, taking Ni enriched water hyacinth (WH, Eichhornia crassipes) as an example, we prepared porous Ni–N doped carbon material (WHPC@Ni) with high supercapacitive performance via fast pyrolysis and KOH activation of WH biomass. The as-prepared WHPC@Ni exhibited an excellent capacitance (552 F g–1 in 6 M KOH) and high stability (97.5% of capacitance remained after 10 000 cycles), which is much higher than its counterpart WHPC–Ni (derived from WH postadsorbed Ni) and ranks it as one of the best reported biomass-based carbonaceous materials. Multiple characterizations and control experiments showed that the small and monodispersed NiO nanoparticles (∼13 nm) in WHPC@Ni played an important role in the enhancement of capacitance. The formation of small NiO nanoparticles may be ascribed to the confinement of organizations of WH (e.g., vessel and cell wall) during the assimilation of Ni, whereas the postadsorbed Ni tended to aggregate during thermochemical treatment (25–85 nm).

Phytoremediation of Nickel via Water Hyacinth for Biocarbon‐Derived Supercapacitor Applications

“…BET physisorption plots ( Figure 2 a) demonstrated type‐IV isotherms characteristic of mesoporous adsorbents where pore networks are relatively disconnected. [ 21 ] Mono‐ and multilayer adsorption of N 2 leads to pore condensation corresponding to the final plateau detected in Figure 2a. [ 24 ] Isotherms presented resemble similar characteristics to a study conducted by Sima et al where embedded Ni and N doped biocarbon was investigated for electrochemical applications.…”

“…[ 24 ] Isotherms presented resemble similar characteristics to a study conducted by Sima et al where embedded Ni and N doped biocarbon was investigated for electrochemical applications. [ 21 ] The surface areas of WH‐0, WH‐5, and WH‐10 biocarbon were determined to be 3031, 3429, and 3062 m 2 g −1 , respectively. These large surface areas are attributed to the pre‐formed hierarchical structure of the plant tissue.…”

“…Increased surface areas are highly desirable for biocarbon electrode materials due to the increased electrode–electrolyte interfacial area, which can lessen the overall resistivity of the electrode. [ 21 ] An increase in pore volume for WH‐5 biocarbon (2.13 cm 3 g −1 ) over WH‐0 and WH‐10 biocarbon (1.99 and 1.97 cm 3 g −1 ) was observed due to an increase in porosity. The pore size distribution in Figure 2b demonstrates micro‐ and mesopores pores ranging from about 0.7 to 7 nm with an average pore size ( S p avg ) of 2.6, 2.5, and 2.6 for WH‐0, WH‐5, and WH‐10 biocarbon, respectively.…”

“…The effect of embedded Ni within the cellular tissue of WH and its preliminary significance on electrochemical performance was previously investigated by Sima et al [ 21 ] However, the study presented herein details further examination of Ni 2+ uptake by WH and application in supercapacitors where various concentrations of embedded Ni and its effect are studied. Fundamental understanding of the materials obtained is derived from physical characterizations, including inductively coupled plasma optical emission spectroscopy (ICP‐OES), scanning electron microscopy (SEM), Brunker–Emmet–Teller (BET), attenuated total reflectance Fourier transform IR (ATR‐FTIR), Raman spectroscopy, and X‐ray diffraction (XRD) analyses.…”

Defective S/N co-doped carbon cloth via a one-step process for effective electroreduction of nitrogen to ammonia

“…The change of the NRR performance is consistent with that of S and N content in CC-APS X, conrming that the co-doping of S-N heteroatom pairs may enhance the NRR performance of the carbon through a synergistic effect. [60][61][62] The doping quantity of N in CC-APS 800 is higher than many other N-doped carbon materials prepared through conventional thermochemical methods, [63][64][65] suggesting that introducing S as a secondary dopant may benet the codoping of N in carbon materials. Fig.…”