Energy-saving and product-oriented hydrogen peroxide electrosynthesis enabled by electrochemistry pairing and product engineering

Hydrogen peroxide (H2O2) electrosynthesis through oxygen reduction reaction (ORR) is drawing worldwide attention, whereas suffering seriously from the sluggish oxygen evolution reaction (OER) and the difficult extraction of thermodynamically unstable H2O2. Herein, we present an electrosynthesis protocol involving coupling ORR-to-H2O2 with waste polyethylene terephthalate (PET) upcycling and the first H2O2 conversion strategy. Ni-Mn bimetal- and onion carbon-based catalysts are designed to catalyze ORR-to-H2O2 and ethylene glycol electrooxidation with the Faradaic efficiency of 97.5% (H2O2) and 93.0% (formate). This electrolysis system runs successfully at only 0.927 V to achieve an industrial-scale current density of 400 mA cm−2, surpassing all reported H2O2 electrosynthesis systems. H2O2 product is upgraded through two downstream routes of converting H2O2 into sodium perborate and dibenzoyl peroxide. Techno-economic evolution highlights the high gross profit of the ORR || PET upcycling protocol over HER || PET upcycling and ORR || OER. This work provides an energy-saving methodology for the electrosynthesis of H2O2 and other chemicals.


Economic calculation
In order to clearly prove the economic potential of the hybrid electrolysis system, we conducted a comprehensive techno-economic assessment on different electrolytic configurations.Based on past experience, we first built a relatively suitable techno-economic model to evaluate the product profitability of each system.To better approach the real industrial situation, equipment investment of electrolyzer and supporting facilities, electricity cost, electrolyte and membrane replacement cost, and maintenance cost are included in the calculation scope.In addition, separation costs that cannot be ignored are also included in the evaluation scope.For convenient considerations, the cost calculation parameters of the separation system borrowed the report that has been reported literature.On the basis of the US Department of Energy's recently announced utility-scale solar 2025 cost target 1 , we estimated a cost of renewable electricity of 0.03 USD/kWh and 90% power conversion efficiency 2 .The specific calculation method is as follows.
The main operating conditions are as follows: 150 tons/day PET processing capacity, 10% impurity content, 350 days/year of operation time, 300 mA cm -2 current density, 50% single gas conversion efficiency, 5-year life of equipment, 35 USD/ton O2 purchase price and 390 USD/ton waste PET purchase price 3 .Other operation parameters are as follows: The total current.According to the processing capacity demand of PET waste and Faradaic efficiency (90%) of oxidation process.the required total current is calculated as:  (10)     Capital cost.Since both anode and cathode catalysts are non-precious metal-based materials, and their cost is negligible compared with that of noble metal Pt and Ir.Here, we use 460 USD/kW as the stack cost 4 .The reference electrolyzer operates at 1.75 V and 0.4 A cm -2 and the installation factor is 1.12.The balance of plant (BoP) cost is assumed to be 35% of the total cost of the electrolyzer system, and these values were derived from the H2A model.
PSA cost is related to the outlet gas flow rate, estimated according to the literature as 1989043 USD/(1000 m 3 /hr) 4 .Considering that the generated formic acid reacts with KOH to form formate, it is necessary to adjust the pH with formic acid first to precipitate PTA, and the supernatant is further sent to a vacuum distillation device for separation to obtain KDF.We assume that the capital cost of the separation process accounts for 20% of the raw material cost 5 3. Cost of liquid product separation.Under conventional circumstances, the complexity and high energy consumption limit the separation of hydrogen peroxide from alkaline electrolyte to a certain extent.However, the electrolyte containing H2O2 proposed in this study can be directly used for the downstream production of sodium peroxyborate and dibenzoyl peroxide, which avoids the separation problem.The converting from H2O2 to SPB and BPO can achieve profit growth.To simplify the economic evaluation and conduct parallel comparisons, we exclude both the raw material cost (borax, benzoyl chloride) and the product values (SPB, BPO).For the separation of anode products, the corresponding equipment cost can be assumed to be 20% of the raw material cost.
Operating cost.The working and maintenance cost was assumed to be 2.5% of the capital cost.According to the literature, membrane cost can be equivalent to 180 USD/m 2 when reference operating conditions are considered.As mentioned above, the separation of cathode products need not be considered, but the purification of anode PTA and KDF is an energy intensive separation process.Thus, we assume the utilities cost account for 60% of the raw material cost 5 .Given the loss of electrolyte due to neutralization, it is assumed that the consumption cost of electrolyte and water accounts for 30% of the cost of raw materials.

Electricity
Capital cost.Similar to the ORR//PET oxidation system, 460 USD/kW can be used as the stack cost.In contrast, the anode products are all gas phase, so no liquid separation device can be ignored. .

O2 flow rate at anode side.
6,7ed on market prices and literature references, the selling prices of KDF, PTA, and H2O2 are set at 1590 USD/ton, 1260 USD/ton,3and 1200 USD/ton6,7.For cross-sectional comparison, the PET throughput and operating conditions of the plant are consistent with the above strategy.Other operation parameters and economic data are as follows: Faraday efficiency of the anode product O2 can be assumed to be 100%.
Other cost.Other cost, such as operating overhead, labor-related cost and selling (or transfer) expense, account for 20% of the cost of raw materials.

Green hydrogen production coupled with PET upcycling.
Many data including processing capacity and equipment parameters are consistent with the above system.Assuming that the Faradaic efficiency of the cathode H2 is 100%, the market price of hydrogen is 1900 USD/ton.Under ideal conditions, hydrogen as the only product of the cathode does not need to be separated by pressure swing adsorption, so only the liquid phase product needs Other cost.Since the HER//EOR system is simpler in process and equipment than the ORR//PET oxidation system, we assume that other costs account for 10% of the cost of raw materials.