Enabling direct H2O2 electrosynthesis of 100 % selectivity at 100 mA cm−2 using a continuous flow sulfite/air fuel cell
Graphical abstract
Introduction
Hydrogen peroxide (H2O2) is widely used as a versatile and eco-friendly oxidant in a variety of industries, e.g. chemical and medical industries, and environmental governance [1], [2], [3]. Today, almost 99 % of H2O2 is manufactured via the energy-intensive multi-step anthraquinone method, which requires large-scale infrastructure and expensive palladium catalysts, as well as by-produces vast waste [4], [5], [6]. In response, an alternative route for direct production of H2O2 through the electrochemical 2e− oxygen reduction reaction (ORR) route has largely developed [7], [8], [9], [10].
The electrochemical approach can be driven by renewable power for on-site H2O2 production, which is one-step, easy operation, under moderate conditions, suitable for various scale applications, and require simple devices [4], [11].
Recently, research on H2O2 electrosynthesis includes catalyst development, reaction engineering, reactor development, and parameter optimization [5], [7], [12]. Extensive researchers have focused on catalyst synthesis [4], [5], [7], e.g. Pd-based catalysts, carbon-based materials, and MNC single-atom catalysts. Carbon-based materials are promising catalysts for H2O2 electrosynthesis, as they are cost-effective, earth-abundant, and electrochemically stable [5], [6]. They allow the incorporation of a variety of functional groups through various well-developed methods to further enhance activity and selectivity [1], [4]. For example, Zhu et al. [13] reported a KOH-treated reduce method to induce the etheric group (COC) on the surface of graphene oxide, which can achieve 100 % selectivity for H2O2. Except for the catalyst, anode reaction and reactor configuration greatly affect H2O2 production and energy consumption [11], [14]. H-cells are widely used in the evaluation of catalysts. But it cannot represent the accurate performances of catalysts or electrodes for industrial applications, because it is non-continuous and scalable [7]. The flow filter-press cell is a promising structure for the H2O2 electrosynthesis reactor [11], [14]. The filter-press cell is one of the fully developed electrochemical reactors in electrochemical industries, e.g. fuel cell, water electrolysis, and electrosynthesis [15]. Xia et.al. [2] developed a self-driven H2/O2 fuel cell using a solid electrolyte filter-press cell to direct electrosynthesis up to 20 wt% pure H2O2 solution. Besides, several other reactor configurations have been developed for pollution degradation, such as rotating disc reactor [16], and jet-cell [17]. Nevertheless, the published energy consumption of H2O2 electrosynthesis was in the range of 6.0–22.1 kWh kg−1, which was much higher than the anthraquinone route [11], [17], [18]. Moreover, the electrosynthesis of H2O2 generally suffered low productivity, 0.05–0.12 mmol cm−2h−1 today [2], [14].
Our goal is to develop a promising method to enhance H2O2 productivity and reduce energy consumption. Herein, we propose a strategy to reduce the cell voltage by replacing the traditional oxygen evolution anode with a sulfite depolarized anode, which can operate as a sulfite/air fuel cell [19], [20]. As presented in Fig. 1, the theoretical cell voltage drop is −0.509 V in an alkaline medium. For win–win goals, we choose the desulfurization solution from the ammonia flue gas desulfurization process as an anolyte, which not only reduces the cost of the reagent but also achieves resource recovery from waste. Moreover, we also test and compare the influence of some usual active methods for the 2e−-ORR activity of Vulcan XC-72R carbon material. 100 % selectivity of H2O2 electrosynthesis at 100 mA cm−2 is achieved using a homemade prototype cell.
Section snippets
Preparation of active Vulcan XC-72R
The commercial carbon powder Vulcan XC-72R from Cabot Corporation (USA) was used as the ORR catalyst in this work. For a proper activation method, several calcining activation methods and hydrothermal activation methods were investigated. The Vulcan XC-72R was calcined at 600 °C in air or nitrogen atmospheres using a tube furnace (HF-kejing, OTF-1200X) for 3 h respectively [21]. The hydrothermal pretreatment was carried out by adopting 5 wt% HNO3 solution, 0.07 mol/L H3PO4 solution, 0.2 mol L−1
Characterizations of the Vulcan XC-72R catalysts
The untreated and treated Vulcan XC-72R carbon powders were characterized by FTIR and XPS to reveal the surface functional groups. FTIR spectra are present in Fig. 2. The FTIR signals were contributed from hydroxyl (C-OH), ketonic species (CO), carboxyl (COOH), sp2-hybridized CC, epoxide (COC), various CO and CO containing chemical species [4], [33]. The CO and CO containing chemical species contains lactol, peroxide, dioxolane, anhydride, and cyclic ether [4], [33]. All FTIR spectra exhibit
Conclusions
In this article, we propose a strategy to directly synthesize hydrogen peroxide using a continuous flow sulfite/air fuel cell. It is demonstrated here that replacing the traditional oxygen evolution anode with a sulfite depolarized anode not only reduces energy consumption but also enhances productivity. First, we evaluated the commercial carbon powder Vulcan XC-72R activated with several calcining and hydrothermal methods. Electrochemical tests show the sample treated with KOH solution
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This research is funded by the Ministry of Science and Technology of The People's Republic of China, via National Key Research and Development Programs (2020YFC1908704 and 2022YFC3202702). The authors would like to acknowledge the Thousands Youth Talents Project of China, which sponsors Prof. Xu Wu.
References (41)
- et al.
Selective H2O2 electrosynthesis by O-doped and transition-metal-O-doped carbon cathodes via O2 electroreduction: a critical review
Chem. Eng. J.
(2021) - et al.
Generation of H2O2 by on-site activation of molecular dioxygen for environmental remediation applications: a review
Chem. Eng. J.
(2020) Bifunctional oxygen/air electrodes
J. Power Sources
(2006)- et al.
Efficient in-situ production of hydrogen peroxide using a novel stacked electrosynthesis reactor
Electrochim. Acta
(2017) - et al.
Hydrogen peroxide generation from O2 electroreduction for environmental remediation: a state-of-the-art review
Chemosphere
(2019) - et al.
KOH-treated reduced graphene oxide: 100% selectivity for H2O2 electroproduction
Carbon
(2019) - et al.
Electrochemical jet-cell for the in-situ generation of hydrogen peroxide
Electrochem. Commun.
(2016) - et al.
The effect of carbon support treatment on the stability of Pt/C electrocatalysts
J. Power Sources
(2008) - et al.
The effect of pretreatment of Vulcan XC-72R carbon on morphology and electrochemical oxygen reduction kinetics of supported Pd nano-particle in acidic electrolyte
J. Electroanal. Chem.
(2010) - et al.
Oxygen reduction electrode in brine electrolysis
Electrochim. Acta
(2000)
Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide
Carbon
Double walled carbon nanotube/polymer composites via in-situ nitroxide mediated polymerisation of amphiphilic block copolymers
Carbon
Chemical oxidation of multiwalled carbon nanotubes
Carbon
Surface and structural characterization of multi-walled carbon nanotubes following different oxidative treatments
Carbon
Determination of the kinetic parameters of the oxygen reduction reaction using the rotating ring-disk electrode: part I theory
J. Electroanaly. Chem. Interfacial Electrochem.
Strongly coupled cobalt diselenide monolayers for selective electrocatalytic oxygen reduction to h2o2 under acidic conditions
Angew. Chem. Int. Ed.
Direct electrosynthesis of pure aqueous H2O2 solutions up to 20% by weight using a solid electrolyte
Science
Atomic-level tuning of Co–N–C catalyst for high-performance electrochemical H2O2 production
Nat. Mater.
Building and identifying highly active oxygenated groups in carbon materials for oxygen reduction to H2O2
Nat. Commun.
High-efficiency oxygen reduction to hydrogen peroxide catalysed by oxidized carbon materials
Nat. Catal.
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