Nitrogen, oxygen and phosphorus decorated porous carbons derived from shrimp shells for supercapacitors
Graphical abstract
Introduction
Supercapacitors have attracted great attention owing to their high rate capability, long cycle life, large power density and low maintenance [1], [2]. Based on the different charge-storage mechanisms, supercapacitors can be divided into two categories: one is the electrical double-layer capacitors (EDLCs), as characterized by high power density and long cycle life, in which the capacity arises from the electrosorption of ions on porous carbon (PC) electrodes at the electrode/electrolyte interface [3], [4], [5], [6]. The other is the pseudocapacitors with high energy density but poor power density and cycle stability, its capacity comes from faradaic reactions at the electrode/electrolyte surface [3], [4], [5], [6], [7]. The electrode materials are the key components determining their capacitance performance, and PCs are the most reported electrode materials owing to their large surface area, tunable pore structure and good electrical conductivity [8], [9], [10], [11]. Many strategies have been carried for optimizing the energy density of capacitors while keeping a high power density for supercapacitors [12], [13], and pseudocapacitance materials are important candidates in this respect. Surface-functionalized carbon materials containing heteroatoms such as nitrogen or oxygen exhibit pseudacapacitance due to charge or mass transfer between the electrode and the ions of the electrolyte [14], [15]. It is known that oxygen functionalities are usually present on the surface of PC as a residue from the carbon source or a result of activation process. The pseudocapacitance contribution of nitrogen to the capacitance of PC has also been widely reported [16]. Various techniques have been focus on the introduction of nitrogen species into the carbon framework, which is achieved either by using nitrogen-containing precursors such as melamine and polyvinylpyridine or via treating carbon materials with ammonia gas [17], [18], [19]. Despite the great efforts on synthesis of nitrogen-doped carbon electrodes with high capacitive performance, the exploration of renewable biomass with lots of heteroatom as raw material to produce electrode materials would be more worthwhile considering the potential scale of supercapacitor applications [20].
Shrimp shell, a kind of food waste in high quantity, is a cheap and reliable biomass source without increasing competition for food. Shrimp shell is composed of nitrogen containing polysaccharide named as chitin (poly-b(1/4)-N-acetyl-D-glucosamine), which can be used as the precursor to directly produce nitrogen doped carbons by pyrolysis technique [21]. However, such carbons usually have poor capacitance when used as the supercapacitor electrode because of their relatively low porosity. Usually, physical or chemical activation of carbon precursors can be used to introduce pores into the resultant carbons, allowing good performance as electrodes for supercapacitors due to the synergistic effect of EDLCs and pseudocapacitors [22], [23]. Herein, we report a simple, sustainable preparation of nitrogen/oxygen/phosphorus (N/O/P) heteroatom decorated PCs via in-situ H3PO4 activation of shrimp shell. Following two advantages brought by H3PO4 as the activating agent can be actualized: (1) Porous structures can be introduced into the carbon materials, thus improve the power density of supercapacitors. (2) Phosphorus atom can be in situ introduced into the carbon framework, which can improve its energy density. As expected, the resultant PCs exhibit good electrochemical performances when used as supercapacitor electrodes.
Section snippets
Synthesis of N/O/P decorated PCs from shrimp shell
After being cooked and eaten, Bohai shrimp shell was used as the raw material in this study. The shell was sufficiently dissolved in 10 wt% HCl solution at room temperature until the complete removal of CaCO3, then recovered by filtration and washed abundantly with distilled water and dried at 80 °C for 4 h. Activation process was performed as follows. Firstly, above treated shell and phosphoric acid (H3PO4, 85 wt%) with a weight ratio of 1:3 were thoroughly mixed together and dried at 80 °C
Results and discussion
Fig. 1 illustrates the strategy for the synthesis of N/O/P decorated carbons with porous structures using shrimp shell as the carbon precursor by one-step H3PO4 activation. CaCO3 in shrimp shell was firstly removed by HCl, then in situ activated by H3PO4 at 400∼600 °C in Ar. PCs with 21-24 wt% of yield were obtained and used as electrode materials for supercapacitors.
Shrimp shell undergoes thermal decomposition and activation by H3PO4 during heat treatment, and lots of heteroatoms including N, O
Conclusions
N, O, P heteroatom decorated PCs for supercapacitors have been successfully prepared by one step H3PO4 activation of shrimp shell. The contents of N, O and P functional groups in the resultant PCs along with their porosities are temperature-dependent. PCs with abundant pores and heteroatom functionalities are good electrode materials for supercapacitors. N, O, P decorated PCs with suitable porous structure exhibit good capacitive behaviors, including large capacitance, long cycle life, high
Acknowledgements
This work is supported by the NSFC (Nos. 51372277, 50902066), China Postdoctoral Science Foundation (2013M530922, 2014T70253) and Program for Liaoning Excellent Talents in University (LJQ2014118) and the Fundamental Research Funds for the Central Universities (No.15CX08005A).
References (37)
- et al.
Electrochemical flexible supercapacitor based on manganese dioxide-titanium nitride nanotube hybrid
Electrochim. Acta
(2014) - et al.
Design and synthesis of heteroatoms doped carbon/polyaniline hybrid material for high performance electrode in supercapacitor application
Electrochim. Acta
(2014) - et al.
Enzymatic synthesis of polyaniline/multi-walled carbon nanotube composite with core shell structure and its electrochemical characterization for supercapacitor application
Electrochim. Acta
(2014) - et al.
Efficient preparation of biomass-based mesoporous carbons for supercapacitors with both high energy density and high power density
J. Power Sources
(2013) - et al.
Phosphorous and nitrogen dual heteroatom doped mesoporous carbon synthesized via microwave method for supercapacitor application
J. Power Sources
(2014) - et al.
NH3-activated polyaniline for use as a high performance electrode material in supercapacitors
Electrochim. Acta
(2012) - et al.
Carbon nitride films deposited from organic solutions by electrodeposition
Diamond Relat. Mate.
(2000) - et al.
Nitrogen-doped graphene quantum dots with oxygen-rich functional groups
J. Am. Chem. Soc.
(2012) - et al.
P/N co-doped microporous carbons from H3PO4-doped polyaniline by in situ activation for supercapacitors
Carbon
(2013) - et al.
Nitrogen-doped porous carbon for supercapacitor with long-term electrochemical stability
J. Power Sources
(2013)
Effect of surface phosphorus functionalities of activated carbons containing oxygen and nitrogen on electrochemical capacitance
carbon
Synthesis of starch-derived mesoporous carbon for electric double layer capacitor
Chem. Eng. J.
Carbon materials for chemical capacitive energy storage
Adv Mater
Cation intercalation and high volumetric capacitance of two-dimensional titanium carbide
Science
Strongly coupled inorganic-nano-carbon hybrid materials for energy storage
Chem. Soc. Rev.
Carbon-based supercapacitors produced by activation of graphene
Science
Desolvation of ions in subnanometer pores and its effect on capacitance and double-layer theory
Angew. Chem. Int. Ed.
Carbon nanocages as supercapacitor electrode materials
Adv Mater
Cited by (216)
Preparation of nitrogen-doped biocarbon derived from shrimp shell and its utilization in glucose biofuel cell
2024, Biochemical Engineering JournalMnO<inf>2</inf> porous carbon composite from cellulose enabling high gravimetric/volumetric performance for supercapacitor
2024, International Journal of Biological MacromoleculesMolybdenum chalcogenides for supercapacitor applications: A critical review
2023, Journal of Energy StorageA review of the next-generation biochar production from waste biomass for material applications
2023, Science of the Total Environment