Indirect Oxidation Research Articles

Boosting Electrochemical Degradation of Water Pollutants Using Sulfur‐Rich Porous Polyimide‐Derived Laser‐Induced Graphene Catalytic Membrane

Water pollution is an inevitable concern associated with technological advancement. To address this problem, it is necessary to significantly shorten the manufacturing process of porous materials while enabling effective pollutant removal. Herein, a facile, rapid, and scalable approach is reported to obtain sulfur‐doped hierarchically porous laser‐induced graphene (S‐LIG) as a catalytic membrane with three‐dimensional networks by localized laser irradiation, along with possible adsorption and electrochemical degradation mechanisms for pollutant removal. S‐LIG is derived from sulfur‐containing porous polyimide film which is prepared via thermally induced phase separation followed by stepwise thermal imidization. Methylene blue (MB) adsorption behavior on the S‐LIG membrane closely fits the pseudo‐second‐order and Freundlich isotherm models, suggesting a complex sorption mechanism, including both strong chemical interaction and physical adsorption. Furthermore, S‐doping enhances catalytic activity for generating reactive oxygen species (ROS), aiding MB degradation via indirect oxidation, and improves direct oxidation on the anode by accelerating electron transfer at the electrodes. This results in a stable 93% MB degradation at a low 1.5 V after 24 h. Additionally, the impact of solution pH reveals that electrostatic attraction forces under basic conditions and the high generation of ROS under acidic conditions favor adsorption and electrochemical oxidation.

New insights into the PFAS defluorination performance and mechanism of ultrasound-enhanced electrochemistry with peroxydisulfate electrolyte

Ultrasound (US)-assisted electrochemical oxidation (EO) has previously demonstrated its ability to degrade perfluorooctanoic acid (PFOA). However, the mechanisms of direct electron transfer and indirect oxidation by reactive oxygen species (ROS), as well as the involvement of these ROS, are unclear, particularly with the peroxydisulfate (PDS) electrolyte and the added effect of US. In this study, an US/EO/PDS system was first investigated, achieving nearly 100 % and 80.01 % defluorination for PFOA and perfluorooctane sulfonate, respectively (within 3 h). This US/EO/PDS system exhibited remarkable stability, pH tolerance, and practicality. Further experimental and theoretical studies revealed that the predominant mechanism of PFOA defluorination was indirect oxidation via ROS, rather than direct oxidation at the anode. Although none of these ROS could initiate the degradation of PFOA without additional energy, both ROS (SO4∙- ＞ •OH ＞ 1O2 ＞ O2∙-) and US/EO contributed to the initial step of PFOA defluorination. Furthermore, US enhanced the generation of ROS and the direct oxidation (electron transfer) ability of EO. The electrons were transferred from PFOA to PDS via the electrode assembly. This study clarified, for the first time, the synergistic effect of US/EO/PDS and the involvement of direct and indirect ROS oxidation in defluorination of PFOA, which shows potential for developing US and EO technology for complete degradation of polyfluoroalkyl substances.

Efficient desalination and synergistic toxic organics removal in RO concentrates with electrochemical advanced oxidation processes

A novel Ce-doped Ti4O7 (Ti/Ti4O7-Ce) electrode was fabricated and investigated in treatment of reverse osmosis (RO) concentrates with Electrochemical advanced oxidation processes (EAOPs). Characterization results showed that Ce was successfully incorporated into the Ti4O7, leading to an increase on the hydroxyl radical (•OH) generation and electrochemical stability compared with Ti/Ti4O7. Ti/Ti4O7-Ce electrodes achieved efficient desalination and oxidation of toxic organics, which was mainly attributed to the indirect oxidation induced by electro-generated •OH and change of electrochemical properties. The action of electric field had great effect on desalination process, and the anions in reverse osmosis concentrates (ROC) deposited on the cathode through this action by characterization and analysis. In the treatment, about 10.8–11.2 % of desalination efficiencies can be obtained, and the removal efficiency of toxic organics enhanced with the increase of Ce addition and current density. In the experiments, TOC removal efficiencies were 57 %, 66 % and 69 % under 10, 20 and 30 mA/cm2 in the 180 min treatment. Toxic chemicals, such as alkanes, haloalkanes, etc., were the main components in treatment, and the organic pollutants with medium molecular weight (MMW) (1400 g/mol) and low molecular weight (LMW) (40–230 g/mol) in ROC were removed. Although slight decreased durability was observed due to Ce leaching, Ti/Ti4O7-Ce electrode maintained stable desalination performance and total organic carbon (TOC) removal efficiency within 60 cycles. This study indicated that Ti/Ti4O7-Ce was a promising electrode for synergistic toxic organics removal and desalination in EAOPs.

Efficient removal of ammonia from aqueous solution using coal-based carbon membrane via electrochemical oxidation in the present of chloride ion

To tackle the escalating issue of ammonia nitrogen water pollution, developing efficient removal technologies holds paramount significance. In this work, an electrochemical membrane reactor (EMR) was constructed for the decontamination of ammonia nitrogen wastewater using the coal-based carbon membrane (CCM) as the flow-through anode. The removal efficiency and degradation mechanism of ammonia nitrogen by EMR during the treatment were investigated. It was found that, under applied voltage and in the presence of chloride ions, the CCM exhibited excellent chlorine evolution performance, and as a result, the EMR had excellent ammonia nitrogen removal efficiency. The removal of ammonia nitrogen by the flow-through EMR was following the pseudo-first-order kinetics. Analysis revealed that various operating parameters, including applied voltage, chloride ion concentration, flow rate, pH value, and initial ammonia concentration, all significantly influenced the ammonia nitrogen treatment performance of EMR. At optimal operation conditions (feed concentration of 30 mg/L, applied voltage of 2.8 V, NaCl concentration of 0.1 mol/L and flow rate of 2 ml/min), the EMR achieved a removal rate of 100 % for ammonia nitrogen with a low energy consumption (EC) of 0.0380 kW•h/g-NH4-N. The degradation mechanism analysis revealed that the primary means of ammonia removal relied on indirect oxidation mediated by OCl·, which was generated by the oxidation of Cl- on the surface of CCM within the solution under the influence of the electric field. Furthermore, the EMR demonstrated good applicability across various water matrices. In conclusion, the EMR holds considerable potential for the decontamination of ammonia nitrogen-containing wastewater.

Platinum modification of metallic cobalt defect sites for efficient electrocatalytic oxidation of 5-hydroxymethylfurfural

Co3O4 possesses both direct and indirect oxidation effects and is considered as a promising catalyst for the oxidation of 5-hydroxymethylfurfural (HMF). However, the enrichment and activation effects of Co3O4 on OH− and HMF are weak, which limits its further application. Metal defect engineering can regulate the electronic structure, optimize the adsorption of intermediates, and improve the catalytic activity by breaking the symmetry of the material, which is rarely involved in the upgrading of biomass. In this work, we prepare Co3O4 with metal defects and load the precious metal platinum at the defect sites (Pt-Vco). The results of in-situ characterizations, electrochemical measurements, and theoretical calculations indicate that the reduction of Co–Co coordination number and the formation of Pt–Co bond induce the decrease of electron filling in the antibonding orbitals of Co element. The resulting upward shift of the d-band center of Co combined with the characteristic adsorption of Pt species synergically enhances the enrichment and activation of organic molecules and OH− species, thus exhibiting excellent HMF oxidation activity (including a lower onset potential (1.14 V) and 19 times higher current density than pure Co3O4 at 1.35 V). In summary, this work explores the adsorption enhancement mechanism of metal defect sites modified by precious metal in detail, provides a new option for improving the HMF oxidation activity of cobalt-based materials, broadens the application field of metal defect based materials, and gives an innovative guidance for the functional utilization of metal defect sites in biomass conversion.

Enhanced degradation of micropollutants using In situ electrogenerated sulfate radical at high flux

The degradation of micropollutants via in situ-generated reactive species from coexisting substances in water is a promising approach for advanced water treatment. However, treatment efficiency and practical applications are hindered by limited operation conditions and prohibitive costs, respectively. Herein, we report an upgraded electrochemical filtration system that is chemical-free and made efficient by achieving in situ SO4•– generation at enhanced flux and in complicated water matrices. The ion transport was enhanced by coupled electric and flow fields, providing an outstanding performance in removing micropollutants. At the optimized conditions, the proposed system degraded 90.5% of bisphenol A (BPA) in 40 min and its degradation kinetics was 14.7 times that of the batch mode, and the treatment efficiency of the proposed system was 2.5 times more efficient than our previous design because of the enhanced flux. Quenching experiments indicate that indirect oxidation by SO4•– and •OH as well as direct electron transfer play critical roles during the BPA degradation. Importantly, the proposed system does not need any added chemicals and uses only the ubiquitous SO42− and electricity. From an environmental point of view, its energy conservation and the lack of additional chemicals ensure its applicability for purifying micropollutants.

An Electrosynthesis of 1,3,4-Oxadiazoles from N-Acyl Hydrazones.

The 1,3,4-oxadiazole is a widely encountered motif in the areas of pharmaceuticals, materials, and agrochemicals. This work has established a mild, mediated electrochemical synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from N-acyl hydrazones. Using DABCO as the optimal redox mediator has enabled a mild oxidative cyclisation, without recourse to stoichiometric oxidants. In contrast to previous methods, this indirect electrochemical oxidation has enabled a broad range of substrates to be accessed, with yields of up to 83%, and on gram scale. The simplicity of the method has been further demonstrated by the development of a one-pot procedure, directly transforming readily available aldehydes and hydrazides into valuable heterocycles.

Simultaneously Boosting Direct and Indirect Urea Oxidation of Nickel Hydroxide via Strategic Yttrium Doping.

Urea electrolysis can address pressing environmental concerns caused by urea-containing wastewater while realizing energy-saving hydrogen production. Highly efficient and affordable electrocatalysts are indispensable for realizing the great potential of this emerging technology. Among the numerous candidates, α-Ni(OH)2 has the merits of good electrocatalytic activity, adjustable heteroelement doping, and low cost; consequently, it has received tremendous attention in the electrolytic fields. Herein, a Y3+-doping strategy is developed to effectively enhance the catalytic performance of nickel hydroxide in the urea oxidation reaction (UOR). Our results show that Y3+ incorporation successfully modulates the electronic structure of α-Ni(OH)2 by inducing Ni3+ formation in the crystal lattice to initiate direct UOR, facilitates the Ni3+/Ni2+ redox transition with higher current responses to promote indirect UOR, and maintains the structural stability of YNi-10 (Ni2+/Y3+ molar ratio = 1:0.1) during long-term UOR operation. Owing to these features, the obtained YNi-10 sample exhibits a higher current density (127 vs 79 mA cm-2 at 1.5 V), a lower Tafel slope (48 vs 75 mV dec-1), a larger potential difference between the UOR and oxygen evolution reaction (OER, 0.26 vs 0.22 V at 80 mA cm-2), a higher reaction rate constant (1.1 × 105 vs 3.1 × 103 cm3 mol-1 s-1), and a reduced activation energy of UOR (2.9 vs 14.8 kJ mol-1) compared with the Y-free counterpart (YNi-0). This study presents a promising strategy to simultaneously boost direct and indirect UORs, providing new insights for further developing high-performance electrocatalysts.

Energy-saving and benign hydrogen production by coal gasification fine slag-assisted Water electrolysis

ABSTRACT Integrating anodic coal gasification fine slag oxidation with cathodic hydrogen evolution reaction presents an environmentally friendly and energy-efficient solution for solid waste recycling and hydrogen production. This innovative approach exhibits higher activity and stability than conventional water electrolysis, while also preventing anode degradation due to its benign reaction conditions. The kinetic investigations have revealed that slag oxidation occurs more rapidly than water oxidation. Specifically, slag undergoes direct and indirect oxidation within the potential regions below and above those of water oxidation, respectively. This study has the potential to shed light on the mechanisms underlying slag electrolysis and offer valuable insights for the simultaneous recycling of solid waste and hydrogen production.

Enhancing the Electrocatalytic Oxidation of 5-Hydroxymethylfurfural Through Cascade Structure Tuning for Highly Stable Biomass Upgrading

HighlightsA novel cascade strategy is proposed to construct Pd-NiCo2O4 electrocatalyst.First time discovery that Ni incorporation together with Pd loading is able to balance the competitive adsorption of OH– and 5-hydroxymethylfurfural.Pd–NiCo2O4 promotes both the indirect and direct synergistic oxidation process.Pd–NiCo2O4 catalyst exhibits extraordinary current density and excellent Faradaic Efficiency at a low potential.

Carbon Nanosheet Preparation By Low-Temperature Two-Step Carbonization: A Study of Their Properties and Mechanism of Adsorption of Oxidized H2S.

Straw, as a kind of biomass waste, has the advantages of low cost and abundant storage, which makes it a promising renewable resource. Using rice straw as a carbon source, carbon nanosheets were prepared by a two-step carbonization method combining low-temperature pyrolysis and low-temperature hydrothermal, and they were used as H2S removal agents. The results showed that during the two-step carbonization process, the adsorption performance of carbon nanosheets for H2S showed a tendency of enhancing and then weakening with the increase of pyrolysis temperature in the first step, and the sulfur capacity could reach 3.1 mg/g at the maximum of the pyrolysis temperature of 200 °C, which was superior to or close to that of the modified or activated carbon. The XPS, EPR, and CO2-TPD tests showed that the surface of carbon nanosheets was alkaline, containing a large number of hydroxyl groups and the presence of phenoxy persistent free radicals or semiquinone persistent free radicals. It was analyzed that the direct or indirect oxidation of H2S by the persistent radicals under an alkaline environment could convert the -2-valent sulfur into -1-, 0- and +6-valent sulfur to realize the adsorption and removal of H2S. This work, while offering the possibility of utilizing carbon nanosheets made from straw as a material for H2S adsorption and removal, also expands the application of straw waste in exhaust gas treatment.

Photothermal Assisted Biomass Oxidation for Pairing Carbon Dioxide Electroreduction with Low Cell Potential.

Integrating anodic biomass valorization with carbon dioxide electroreduction (CO2RR) can produce value-added chemicals on both the cathode and anode; however, anodic oxidation still suffers from high overpotential. Herein, a photothermal-assisted method was developed to reduce the potential of 5-hydroxymethyl furfural (HMF) electrooxidation. Capitalizing on the copious oxygen vacancies, defective Co3O4 (D-Co3O4) exhibited a stronger photothermal effect, delivering a local temperature of 175.47 °C under near infrared light illumination. The photothermal assistance decreased the oxidation potential of HMF from 1.7 V over pristine Co3O4 to 1.37 V over D-Co3O4 to achieve a target current density of 30 mA cm-2, with 2,5-furandicarboxylic acid as the primary product. Mechanistic analysis disclosed that the photothermal effect did not change the HMF oxidation route but greatly enhanced the adsorption capacity of HMF. Meanwhile, faster electron transfer for direct HMF oxidation and the surface conversion to cobalt (oxy)hydroxide, which contributed to indirect HMF oxidation, was observed. Thus, rapid HMF conversion was realized, as evidenced by in situ surface-enhanced infrared spectroscopy. Upon coupling cathodic CO2RR with an atomically dispersed Ni-N/C catalyst, the Faradaic efficiencies of CO (cathode) and 2,5-furandicarboxylic acid (FDCA, anode) exceeded 90.0 % under a low cell potential of 1.77 V.

Stabilized Hf-doped Ti/Sb-SnO2 electrode for efficient degradation of tetracycline.

The electrochemical advanced oxidation process (EAOP) has shown significant promise in the field of refractory organic wastewater treatment due to its high efficiency and environmentally friendly nature. In this study, Ti/Sb-SnO2 electrodes with varying proportions of Hf were prepared using the sol-gel method. The addition of Hf transformed the original collapsing and broken surface into a flat and regular surface. The results demonstrated that Ti/Sb-SnO2-Hf electrode doped with 6% Hf exhibited a higher oxygen evolution potential (OEP) and excellent stability. The OEP increased from 2.315 V without Hf-doping to 2.482 V, and the corresponding actual life was 321.05% higher than that without Hf. The current density (5-40 mA·cm-2), electrolyte concentration (0.02-0.2 mol·L-1), pH (3-11), and initial pollutant concentration (5-80 mg·L-1) were evaluated to confirm the tetracycline (TC) degradation characterization of Ti/Sb-SnO2-6%Hf electrodes. It was concluded that under the optimal degradation conditions, the removal rate of TC could reach 99.66% within 2 h. The degradation of TC follows first-order reaction kinetics. The oxidative degradation of TC was achieved through indirect oxidation, with ·OH playing a dominant role. TC's electrochemical oxidation degradation pathway has been proposed: Based on LC-MS results, three main pathways are speculated. During the electrocatalytic oxidation process, decarboxylation, deamidation, and ring-opening reactions occur under ·OH attack, producing intermediate compounds with m/z values of 427, 433, 350, 246, 461, 424, 330, 352, 309, 263, and 233. These intermediates are further oxidized to intermediate compounds with an m/z value of 218. This work introduces a new efficient anode electrochemical catalyst for the degradation of TC, providing a strategy for industrial applications.

Optimized electrochemical treatment of semi-coking wastewater for enhanced degradation of biological toxicity using a Ru-Ir-Ti anode and Co-Ti cathode

The Co-Ti cathode was prepared to reduce the biological toxicity of semi-coke wastewater by electrochemical system with commercial ruthenium-iridium titanium (Ru-Ir-Ti) anode. Meanwhile, the removal rate of chemical oxygen demand (COD), volatile phenol (VP) and ammonia nitrogen (NH3-N) in wastewater were also evaluated. Hence, the influence of processing time (A), dilution multiple (B), initial pH (C), electrolyte concentration (D) and current density (D) were systematic explored. After treatment, with the optimized experiment condition of processing time (150 min), dilution multiple (300 times), initial pH (3.2), electrolyte concentration (0.15 mol/L), current density (16 mV/cm2), the B/C value of wastewater was greatly improved from 0.12 to 0.31, the removal rate of COD, NH3-N and VP was 96.82 %, 92.34 % and 97.07 %, respectively. The sequence of significance was B>D>E*E>B*D>A*D>D*D. This most effective degradation was owing to the simultaneously oxidization of both cathode and anode, turning the highly biological toxic wastewater to the biodegradable one. The direct oxidation reaction happened on anode, furthermore, the indirect oxidation reaction would be accelerated near the cathode because of active free radicals generation such as ·OH and O2•– when the cobalt’s valence changed from +2 to +3. It deserve to be mentioned in this research is that the direct and indirect oxidation simultaneously contributed to the degradation of biological toxicity, which is great beneficial for the further bio-chemical processing.

Differences in anodizing of two copper-containing coordination compounds by different degradation factors: Experiments and DFT calculations

Copper phthalocyanine (CuPc) and copper formazan (CuFz) are typical coordination compounds widely utilized due to their physicochemical properties and biochemical behavior. The production and application of CuPc and CuFz have produced large amounts of copper-containing wastewater and aromatic organics, posing great risks to human health and the environment. This research introduced a feasible and efficient treatment method based on BDD anodic oxidation for CuPc and CuFz wastewater and provided a novel perspective on the degradation differences of the two pollutants through DFT calculation. Firstly, the color removal efficiency and chemical oxygen demand (COD) during the anodic oxidation of the two molecules were compared. Secondly, the effect of pH, inorganic anions type, and current density on the oxidative degradation of CuPc and CuFz was discussed. Thirdly, cyclic voltammetry (CV) was carried out to evaluate the direct anodic oxidation speed of CuPc and CuFz. Then, the principal reactive oxygen species (ROS) of CuPc and CuFz in the indirect oxidation process were investigated through free radical quenching and Electron paramagnetic resonance (EPR) spectroscopy. The functional group changes in degradation, the degradation products, and the shed copper ions were also analyzed. Finally, the global, local, and condensed properties and CuPc and CuFz reaction sites to be attacked by ROS were theoretically analyzed using density functional theory (DFT) calculation. Altogether, this study can help broaden the discussion and further the understanding of the links between the electrochemical oxidation pathway and decolorization of coordination compounds.

Enhanced bacterial and virus disinfection with copper nanoparticle optimized LIG composite electrodes and filters

Waterborne pathogens pose a lifelong threat, necessitating advanced disinfection systems with state-of-the-art materials. Laser-Induced Graphene (LIG), a 3-dimensional form of graphene, is a widely known electrode material for its electrically-induced antimicrobial properties. However, LIG surfaces exhibit antimicrobial properties exclusively in the presence of electricity. In this work, copper-doped LIG (Cu-LIG) composite electrodes and filters were developed with enhanced antimicrobial properties in single-step laser scribing. The work emphasizes the optimization of copper doping with LIG for both electrical and non-electrical-based disinfection. The copper doping was optimized to a minimal concentration (∼1%) just to enhance the electrochemical properties of LIG. Furthermore, the excess addition of copper was helpful towards non-electricity-based treatment without significant leaching. The prepared surfaces were tested in both electrodes and filter configuration and showed excellent antibacterial and antiviral activity against mixed bacterial culture and a model enteric virus, MS2 bacteriophage. On the application of 2.5 V with Cu-LIG electrodes, 6-log removal of bacteria and virus was achieved. Furthermore, the membrane-based electroconductive filters were tested in a flow-through configuration and demonstrated 6-log removal at 2.5 V with a flux of ∼ 500 L m2 h−1 with both bacteria and viruses at minimum energy expense. Additionally, reactive oxygen species scavenging and hydrogen peroxide generation experiments have confirmed the role of electrical effects and indirect oxidation on the inactivation mechanism. The prepared Cu-LIG composite surfaces showed potential for environmental remediation applications.

Synthesis of multifunctional Ti/RuO2-ZnO composite catalytic electrodes for electrochemical oxidation and hydrogen production from toluene-containing wastewater

Developing electrodes that effectively perform indirect oxidation on nondecomposable organic compounds is a key objective in electrochemical oxidation research. This study focuses on fabricating a Ti/RuO2-ZnO electrode through a simple pyrolysis method on a Ti substrate etched with hydrochloric acid. Hydrochloric acid etching played a pivotal role in enhancing coating stability by markedly increasing the Ti substrate's surface area and hydrophilicity. Analyzing the linear sweep voltammetry revealed that the electrode exhibited a low overvoltage of the oxygen evolution reaction, reaching 221 mV at 10 mA cm−2, indicating effective use as an active anode. The electrode's performance was evaluated by removing toluene contained in a 0.1 M NaCl solution at pH 5. The electrochemical reaction generated active chlorine in the solution, oxidizing 98.66 % of toluene over 3 h and concurrently producing 25.62 mL of hydrogen. This study presents a simple and effective synthesis of a RuO2-based active anode, demonstrating its potential application not only in removing toluene from wastewater but also in hydrogen production.

Electromediated Alcohol-Based Passerini-Type Reaction

AbstractAn electrochemical variant of the alcohol-based oxidative Passerini reaction is reported here. It relies on an indirect anodic oxidation process followed by a three-component coupling, in which TEMPO serves as a key redox mediator. This electrochemical approach permits to operate without the need for a metal catalyst nor oxygen atmosphere and allows the use of nonactivated alcohols as reaction partners. It could be applied to the preparation of good variety of α-acyloxy-carboxamides in yields ranging from 24% to 80%.

Degradation of Sodium Acetate by Catalytic Ozonation Coupled with MnOx/NiOOH-Modified Fly Ash.

Fly ash, a type of solid waste generated in power plants, can be utilized as a catalyst carrier to enhance its value-added potential. Common methods often involve using a large amount of alkali for preprocessing, resulting in stable quartz and mullite forming silicate dissolution. This leads to an increased specific surface area and pore structure. In this study, we produced a catalyst composed of MnOx/NiOOH supported on fly ash by directly employing nickel hydroxide and potassium permanganate to generate metal active sites over the fly ash surface while simultaneously creating a larger specific surface area and pore structure. The ozone catalytic oxidation performance of this catalyst was evaluated using sodium acetate as the target organic matter. The experimental results demonstrated that an optimal removal efficiency of 57.5% for sodium acetate was achieved, surpassing even that of MnOx/NiOOH supported catalyst by using γ-Al2O3. After loading of MnOx/NiOOH, an oxygen vacancy is formed on the surface of fly ash, which plays an indirect oxidation effect on sodium acetate due to the transformation of ozone to •O2- and •OH over this oxygen vacancy. The reaction process parameters, including varying concentrations of ozone, sodium acetate, and catalyst dosage, as well as pH value and the quantitative analysis of formed free radicals, were examined in detail. This work demonstrated that fly ash could be used as a viable catalytic material for wastewater treatment and provided a new solution to the added value of fly ash.

The differences between the hydrogenation by means of photon-injection and electron-injection for N-type tunnel oxide passivated contacts solar cells

Tunnel Oxide Passivated Contact (TOPCon) solar cells have received widespread attention in recent years, especially in improving conversion efficiency. This paper investigated the impact of hydrogenation technology using photon-injection (HPI) and electron-injection (HEI) processes on TOPCon solar cells, highlighting the higher improvement effect and broader application scope of HPI compared to HEI. In TOPCon cells, several methods are available to prepare the tunneling oxide layer, such as plasma oxidation (PO) and indirect thermal oxidation (TO). The research results indicated that significant improvement differences could be observed when utilizing the HEI treatment for TOPCon solar cells prepared by PO and TO methods, with values of 0.133%abs. and −0.039%abs., respectively. Meanwhile, HPI treatment induced a more significant efficiency improvement for these two types of cells, and the increase in efficiency is 0.247%abs. and 0.244%abs., respectively. The experimental results demonstrated that the passivation effect for TOPCon solar cells prepared by PO and TO methods remained almost the same under the HPI treatment, and the improvement effect is less dependent on the tunnel oxidation technique used. Thus, the different passivation effects between HPI and HEI were further investigated, and the reason for the difference was attributed to the charge states and concentrations of hydrogen and non-equilibrium carriers during the hydrogenation. The results provided an improved scheme for enhancing the efficiency of TOPCon solar cells, shedding light on the role of HPI and HEI in the passivation process. This work brings further insights to TOPCon solar cells.