Total Absorption Research Articles

A top-mounted, chain-driven, bidirectional point absorber type wave energy convertor

The aims of this paper are to introduce the structure of a point absorber type wave energy convertor (WEC) mounted above sea level, to analyze the motion characteristics and power absorptions of such a WEC and to describe the numerous advantages of installing it in the nearshore. The motion equation is solved by representing the excitation force with the dynamic wave pressure and obtaining an approximate system transfer function. The possibility of the buoy becoming airborne or submerged is considered and the power absorption is increased optimally by reshaping the frequency response using a flywheel. The time, phase and spectral averages of power absorptions are presented for offshore waves, nearshore waves and for concentrated nearshore waves using standard wave spectrums and compared. Approximate gains possible with linear and rectangular arrays are also presented. Considering different phase distributions, it is shown that downgrading WECs based on short term power absorptions is not justifiable. With a buoy of radius 2 m, the power absorption of this kind of a WEC is estimated to be about 114 kW in the deep sea and 117 kW in the nearshore, when the energy flux is about 31 kW/m. By concentrating just 13.6 kW/m nearshore waves, it could be increased to 186 kW. If a 3-element longshore in-line array is placed inside the wave concentrator, the total power absorption could be about 556 kW. A 9-element rectangular array would be capable of absorbing about 1 MW by making use of the remaining energy of the down wave.

Analysis of high-frequency limit in absorption cross-section for Kerr–Newman–de Sitter black hole

In this paper, we study the critical impact parameter and Lyapunov exponent for a massive charged particle and a photon in the Kerr–Newman–de Sitter (KNdS) spacetime. From the geodesic equations obtained for the particle traveling parallel to the rotation axis (on-axis) of the KNdS spacetime and using the complex angular momentum (CAM) technique, it is found that the total absorption cross-section at a high-frequency limit oscillates with decreasing amplitude. We show that the black hole charge and spin affect the total absorption cross-section in the case of both the massive charged particle and photon.

Multi-functional switchable terahertz metasurface device prediction by K-nearest neighbor

In this paper, we present the design of a versatile terahertz (THz) device characterized by its multi-functional capabilities including broadband absorption and polarization modulation, achieved through leveraging the temperature-induced phase transition behavior of vanadium dioxide (VO2). Operating in the metallic state of VO2, the device exhibits broadband absorption properties, delivering a remarkable total effective absorption of 2.871 THz with absorption rates exceeding 90 % across the frequency ranges of 8.140∼9.405 THz and 12.740∼14.346 THz. Furthermore, it demonstrates excellent adaptability to large angle incidence. Conversely, in the dielectric state of VO2, the device transitions into a polarization modulation mode, facilitating linear-to-cross-polarization (LTX) and linear-to-circular-polarization (LTC) conversions. Notably, for LTX polarization, the conversion efficiency exceeds 90 % within the 8-11.5 THz range, while for LTC polarization, the ellipticity surpasses 0.8 within the 7.861∼8 THz range. Additionally, we introduce a machine learning (ML) approach to optimize the device parameters, presenting a novel strategy for enhancing the design and optimization of future multifunctional devices.

Phase change heat storage and enhanced heat transfer based on metal foam under unsteady rotation conditions

Phase change heat storage technology is an essential method for balancing supply and demand in solar energy heat utilization. In this study, a numerical model of the phase change heat storage process is built to explore the impact of non-constant rotation, with and without metal foam. Subsequently, an investigation into the influence of metal foam pore density and porosity on heat storage performance is conducted, with a focus on Taguchi design for statistical analysis. The research delves into the effects of foam parameters on heat storage rate, temperature response, heat storage time, and heat storage properties. Findings reveal significant resolidification in the melting process of this thermal storage structure without metal foam, due to periodic rotation speed hindrance in transferring heat to the outside. Taguchi design results underscore the greater influence of porosity on the melting time and average heat storage rate compared to pore density. Specifically, a reduction in melting time by 62.21 % and 30.49 %, and an increase in average heat storage rate by 237.56 % and 51.19 % is observed when pore density and porosity are 40 PPI and 0.97, compared with the ones with porosities of 0.99 and 0.98, demonstrating minimal impact on total heat absorption.

Absorption of ultrashort laser pulses in medium with account for propagation effects

The absorption of ultrashort laser pulses in an optically dense medium is theoretically studied based on the total absorption coefficient over the entire duration of the pulse, taking into account the effects of propagation and reflection of pulse from vacuum/medium interface. The approach is the generalization of our previous work (available at: www.nobelprize.org/prizes/physics/2023/summary), which traced a ‘bridge’ between the micro- and macro-description of radiation processes in a medium induced by electromagnetic pulses of arbitrary duration. The expression for the total absorption coefficient is obtained in terms the complex refractive index of the medium. Various limits of this expression are considered. Numerical calculations of the dependence of the total absorption coefficient on the parameters of the laser pulses and the thickness of the medium layer were carried out and the results obtained were discussed.

An Improvement of Hand Press Machine by Design for Manufacturing and Assembly (DFMA) Methodology

This research consists of the analysis of hand press machine selected using the Design for Manufacturing and Assembly (DFMA) method. DFMA is a method that combines both Design for Manufacturing (DFM) and Design for Assembly (DFA) techniques. It has the purpose to make improvements on the existing product by implementing DFMA to reduce number of components, time, and cost. The combination of hand press machine and a die cutting tool has been an effective tool to produce and replicate identical designs in the shortest time. The main objective of this research is to develop a Hand Press Machine that exhibits superior design efficiency and reduced manufacturing costs compared to the original design. To achieve this, the chosen existing model, the WUTA Pro Leather Cutting Machine, was remodelled using SolidWorks 2022 software. The original design of the Hand Press Machine had a design efficiency of 25.89%. However, the improved design achieved a significantly higher design efficiency of 36.56%, representing an increase of 10.67%. To attain this improvement, four modifications were implemented. One notable achievement in the improved design was a reduction in the total number of parts. The original design comprised 52 parts, whereas the improved design successfully reduced this to 34 parts, resulting in a reduction of 18 parts. The cost analysis, based on total absorption cost, revealed that the manufacturing cost of the original design was estimated at $362.01 for 18 manufactured parts. In contrast, the improved design was able to achieve a cost reduction, with an estimated manufacturing cost of around $339.16 for 16 manufactured parts. This indicates a cost reduction of $22.85 between the two models.

Deformation mode and energy absorption of self-assembly CFRP composites cellular structure by 3D printing

Compared with traditional cellular structures, self-assembly structures exhibit significantly higher assembly flexibility, allowing for more scientific and rational protection design in the realm of structural protection. Moreover, self-assembly structure had the potential to mitigate the rapid decrease of load bearing capacity often observed in integral molding due to plastic hinge failure between adjacent cells. Therefore, self-assembly CFRP composites cellular structure was proposed, Quasi-static compression test and finite element simulation were carried out to analyze the deformation modes and energy absorption characteristics. Hexagon (H) structure formed a shear failure band, and re-entrant (R) structure was fully densified with large deflection. The deformation of inclined struts of HR and RH structures were well compatible. The total absorption energy of R structure was max, and H structure was min. The specific energy absorption and mean compression force of two-layer structures were higher, but the increasing number of layers could reduce the peak compression force, RH and R structures showed excellent energy absorption ability.

Broadband absorptive metamaterials enhanced by magnetic rubber to broaden bandwidth

A method to extend the operational bandwidth of metal-dielectric-metal (MDM) type absorptive metamaterials is proposed. An ultrathin, five-band absorptive metamaterial with wide-angle absorption and polarization sensitivity in the X-band is designed. The total absorption bandwidth across the five bands, with reflection losses below −10 dB (absorption rate greater than 90 %), is nearly 1 GHz. The physical mechanisms of absorption are analyzed through the distributions of surface current, electric field, and magnetic field. Samples were fabricated and tested, and the results were consistent with the simulation outcomes. To enhance the bandwidth of the absorptive metamaterial and its application prospects, magnetic materials such as barium ferrite and carbonyl iron were introduced into a rubber vulcanization layer, which was then combined with the ultrathin absorptive material to create a novel absorptive material. When the magnetic material content in the rubber layer was 50 wt%, the frequency range with reflection losses below −10 dB increased by approximately nine times, covering 69.5 % of the C-Ku band. This significantly broadens the bandwidth of the pure MDM-type absorptive metamaterial, providing a feasible solution for the design of broadband ultrathin absorptive materials.

Effect of Uncertainty in Water Vapor Continuum Absorption on CO2 Forcing, Longwave Feedback, and Climate Sensitivity

AbstractWe investigate the effect of uncertainty in water vapor continuum absorption at terrestrial wavenumbers on CO2 forcing , longwave feedback λ, and climate sensitivity at surface temperatures Ts between 270 and 330 K. We calculate this uncertainty using a line‐by‐line radiative‐transfer model and a single‐column atmospheric model, assuming a moist‐adiabatic temperature lapse‐rate and 80% relative humidity in the troposphere, an isothermal stratosphere, and clear skies. Due to the lack of a comprehensive model of continuum uncertainty, we represent continuum uncertainty in two different idealized approaches: In the first, we assume that the total continuum absorption is constrained at reference conditions; in the second, we assume that the total continuum absorption is constrained for all atmospheres in our model. In both approaches, we decrease the self continuum by 10% and adjust the foreign continuum accordingly. We find that continuum uncertainty mainly affects through its effect on λ. In the first approach, continuum uncertainty mainly affects λ through a decrease in the total continuum absorption with Ts; in the second approach, continuum uncertainty affects λ through a vertical redistribution of continuum absorption. In both experiments, the effect of continuum uncertainty on is modest at Ts = 288 K (≈0.02 K) but substantial at Ts ≥ 300 K (up to 0.2 K), because at high Ts, the effects of decreasing the self continuum and increasing the foreign continuum have the same sign. These results highlight the importance of a correct partitioning between self and foreign continuum to accurately determine the temperature dependence of Earth's climate sensitivity.

Financial Absorption of Cohesion Policy Funds: How Do Programmes and Territorial Characteristics Influence the Pace of Spending?

AbstractUsing data from the execution of 2014–2020 cohesion policy, this article presents a novel indicator to measure how fast European territories were able to spend their allocated budget and then explores the drivers of such financial performance. This analysis aims to fill a gap in scientific literature as most existing studies tend to focus solely on the total absorption at the end of the period without looking at the average financial performance over time. The article also explores the influence on financial absorption of the governance model (nationally or regionally managed programmes) and the thematic structure of the funds, which has never been done before. The determinants of the speed of financial absorption are investigated through a Tobit model. Results show that both programme‐specific and territorial characteristics are relevant factors in explaining the varying levels of fund absorption. This suggests that increased flexibility in spending rules and the adoption of more tailored strategies could be instrumental in improving fund absorption.

Sulfur-Bridged Asymmetric CuNi Bimetallic Atom Sites for CO2 Reduction with High Efficiency.

Double-atom catalysts (DACs) with asymmetric coordination are crucial for enhancing the benefits of electrochemical carbon dioxide reduction and advancing sustainable development, however, the rational design of DACs is still challenging. Herein, this work synthesizes atomically dispersed catalysts with novel sulfur-bridged Cu-S-Ni sites (named Cu-S-Ni/SNC), utilizing biomass wool keratin as precursor. The plentiful disulfide bonds in wool keratin overcome the limitations of traditional gas-phase S ligand etching process and enable the one-step formation of S-bridged sites. X-ray absorption spectroscopy (XAS) confirms the existence of bimetallic sites with N2Cu-S-NiN2 moiety. In H-cell, Cu-S-Ni/SNC shows high CO Faraday efficiency of 98.1% at -0.65V versus RHE. Benefiting from the charge tuning effect between the metal site and bridged sulfur atoms, a large current density of 550mAcm-2 can be achieved at -1.00V in flow cell. Additionally, in situ XAS, attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), and density functional theory (DFT) calculations show Cu as the main adsorption site is dual-regulated by Ni and S atoms, which enhances CO2 activation and accelerates the formation of *COOH intermediates. This kind of asymmetric bimetallic atom catalysts may open new pathways for precision preparation and performance regulation of atomic materials toward energy applications.

Deformation and energy absorption properties of hollow glass microsphere/polyurethane lightweight core reinforced carbon fiber tubes under lateral compression

AbstractPolyurethane has been widely studied as a lightweight reinforcing material. This paper uses two types of hollow glass microspheres to modify polyurethane in different proportions to prepare a variety of lightweight cores for reinforcing carbon fiber tubes. A quasi‐static lateral compression test was performed on the reinforced carbon fiber tube to analyze the effect of reinforcement materials on mechanical properties, failure modes and crashworthiness. The results show that BR20 reinforcement material has the best effect on enhancing the mechanical properties and crashworthiness of the structure, and its energy absorption is 3.5 times higher than that of carbon fiber tubes. Hollow glass microspheres can improve the reinforcing effect of polyurethane. Lightweight cores prepared from different types of hollow glass microspheres show different failure modes during lateral compression (polyurethane and BR60 show better ductility, and BR20 shows shear failure). The BR20 and BR60 are mixed in different proportions, the reinforced polyurethane foam reinforced carbon fiber tube can have little difference in the energy absorption. The addition of BR20 and BR60 showed a large difference in the force‐displacement curve during the compression stage. A qualitative analysis is conducted based on the effect of the total energy absorption of the structure on the reinforcement materials.Highlights The lightweight core is prepared by hollow glass microspheres and polyurethane. Reinforcement materials enhance the lateral compression performance. Reinforcement materials enhance the crashworthiness performance. Reinforcement materials affect failure modes. The proportion of BR20 and BR60 affects the performance of the lightweight core.

Uncovering the Dissociative Adsorption of the Leveler Janus Green B on Cu Electrodes at the Molecular Level.

The interfacial adsorption structure of an organic leveler decides its functionality in Cu interconnect electroplating and is yet far from clear. In this work, in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and electrochemical quartz crystal microbalance (EQCM) in conjunction with density functional theory (DFT) calculations are applied to unravel the interfacial adsorption of the classic dye leveler Janus Green B (JGB) at a Cu electrode and understand its polarization property against Cu electrodeposition from an adsorption structure perspective. ATR-SEIRAS measurements and DFT calculations reveal that the N=N bond of the JGB molecule splits via reductive hydrogenation, forming two fragments of contrasting adsorption configurations. JGB exhibits the strongest inhibition effect on Cu deposition among all the tested additives including individual and mixed fragments, due to the highest coverage of organic adsorbates from JGB dissociation, as measured by EQCM. This work highlights the advantage of surface sensitive analytical tools in understanding the structure-performance of levelers.

Optimization Study of Fire Prevention Structure of Electric Vehicle Based on Bottom Crash Protection

As the market share of electric vehicles continues to expand, fire accidents due to impacts from the power battery located at the bottom of the electric vehicles are receiving increasing attention. Lithium-ion batteries, as the mainstream choice of power battery for electric vehicles solving the problem that they are prone to thermal runaway due to damage when impacted, are the key to preventing and controlling fire accidents in electric vehicles. To address the protective problem of the bottom power battery of electric vehicles when it is impacted by road debris, two new types of sandwich structures with an enhanced regular hexagonal structure and semicircular arch structure as the core layer, respectively, are innovatively proposed in this article. They are used to protect the bottom power battery of electric vehicles and are compared with the traditional homogeneous protective structure in terms of protective performance. A local finite element simulation (FEM) of an electric vehicle containing the necessary components was established for simulation. Stress distribution, deformation, and energy absorption data for each component of an electric vehicle assembled with a protective structure when subjected to a bottom impact were obtained safely and cost-effectively. Three evaluation coefficients, namely, the cell shape variable (Bcmax), the protective effect parameter (ƒPE), and the total energy absorption of the structure (Ea), are proposed to compare and analyze the simulation results of different protective structures under equal mass conditions. The maximum values of the battery deformation of arched sandwich construction and reinforced honeycomb sandwich construction were 0.35 mm and 0.40 mm, respectively, which are much smaller than that of the maximum deformation of the battery under the protection of a homogeneous protective structure, which is 0.62 mm. Their protective effect parameters are 43.55 and 35.48, respectively, which proves that the optimization degree of the protective structure of the bottom of the electric vehicle after the application of the new structure is 35% or more. The total energy absorptions of the two structures are 91.77 J and 87.19 J, respectively, accounting for more than 70% of the kinetic energy in the system, which proves that the deformation of the sandwich structure can effectively absorb the kinetic energy of the collision between the road obstacle and the bottom of the car. The final results show that the arched sandwich structure showed the best impact resistance in the simulation, which can be used for the power battery’s protective structure on the electric vehicle’s bottom. This study fills a gap in local finite element modeling in electric vehicle crash simulations and provides ideas for fire prevention designs of electric vehicle structures.

Selective crushing, enrichment by friction properties and hydrophobization for obtaining the sustainable blast furnace slag aggregate for road subbase

Air-cooled blast furnace slag is a metallurgical waste that can be used to produce the slag aggregate for pavement subbase. Slag aggregate is much cheaper than natural stone aggregate, but differs in heterogeneity in strength (from 2 to 40 MPa), tendency to absorb water, and low resistance to freezing-thawing. The paper suggests the use of methods of enrichment by friction properties, selective crushing, and hydrophobization to increase slag aggregate resistance to freezing-thawing cycles, crushing, and water penetration. Selection of the most strength (low porous) 75 % slag aggregate grains due to enrichment by friction properties decreases the total water absorption of the sample from 4.45 % to 3.64 %, decreases the sample mass loss after tests for resistance to freezing-thawing cycles from 5.05 % to 2.82 %, reduces the aggregate crushing value (ACV) from 30.71 % up to 23.80 %. Hydrophobization of the pre-enriched slag aggregate additionally reduces its water absorption to 1.08–––1.3 %.

Electrochemical Synthesis of Urea: Co-Reduction of Nitrite and Carbon Dioxide on Binuclear Cobalt Phthalocyanine.

Exploration of molecular catalysts with the atomic-level tunability of molecular structures offers promising avenues for developing high-performance catalysts for the electrochemical co-reduction reaction of carbon dioxide (CO2) and nitrite (NO2 -) into value-added urea. In this work, a binuclear cobalt phthalocyanine (biCoPc) catalyst is prepared through chemical synthesis and applied as a C─N coupling catalyst toward urea. Achieving a remarkable Faradaic efficiency of 47.4% for urea production at -0.5V versus reversible hydrogen electrode (RHE), this biCoPc outperforms many known molecular catalysts in this specific application. Its unique planar macromolecular structure and the increased valence state of cobalt promote the adsorption of nitrogenous and carbonaceous species, a critical factor in facilitating the multi-electron C─N coupling. Combining highly sensitive in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) with density functional theory (DFT) calculations, the linear adsorbed CO (COL) and bridge adsorbed CO (COB) is captured on biCoPc catalyst during the co-reduction reaction. COB, a pivotal intermediate in the co-reduction from CO2 and nitrite to urea, is evidenced to be labile and may be attacked by nitrite, promoting urea production. This work demonstrates the importance of designing molecular catalysts for efficient co-reduction of CO2 and nitrite to urea.

Bimetallic MOFs-derived CoFe/Fe/C particles prepared by explosion and pyrolysis methods for electromagnetic wave absorption

In this study, {[CoFe3O(tza)6(H2O)3]·(NO3)3·5 H2O}n was applied as a precursor for fabricating CoFe/Fe/C composite materials via explosive and high-temperature calcination techniques. The explosive method was identified as a straightforward approach for achieving remarkable electromagnetic wave absorption properties. At a thickness of 2.03 mm, the CoFe/Fe/C (CoFe-700) composite material exhibited a minimum reflection loss of −77.84 dB. Similarly, it demonstrated the widest effective absorption (≦ −10 dB) bandwidth (4.06 GHz) with a thickness of 2.00 mm. Encompassing frequencies from 2.90 GHz to 18 GHz, the total effective absorption bandwidth extended throughout the thickness range of 1.00−5.50 mm. Under the same mixing ratio of powder and paraffin (1:1), the effective absorption bandwidth value of CoFe/Fe/C (CoFe-600) sample at a thickness of 1.40 mm is 4.95 GHz. The CoFe/Fe/C carbon composite materials emerged as optimal electromagnetic wave absorbers due to their exceptional conductivities, abundant dielectric losses, and magnetic loss mechanisms.

Sound propagation in the presence of non-isothermal sheared flow refraction and metasurface impedance reflection

Sheared flow can profoundly influence the aeroacoustic performance of near-wall structures like metasurfaces on moving vehicles. In this work, a refractive generalized Snell’s law is developed by combining Snell’s law with the generalized Snell’s law to manipulate anomalous reflections in an idealized sheared flow, comprising a uniform flow region and a stationary air region with velocity and temperature gradients. Theoretical analysis and numerical simulations of planar wave reflection by metasurface impedance under non-isothermal sheared flows are conducted, yielding favorable predictions of the zone of silence, as well as anomalous and total reflection behaviors. The total reflection between the shear layer and the metasurface is analyzed with the objective of confining incident wave below the shear layer. Remarkably, a specific configuration of hot-sheared flow and metasurface length can achieve total absorption over a range of incident wave angles from 0° to almost 90°. Moreover, the refractive generalized Snell’s law, extended to account for directional deflection induced by flow convection, is utilized to regulate sound beam reflection, resulting in satisfactory outcomes under sheared conditions. This study offers a theoretical framework for wave control under non-isothermal and sheared flow conditions, which cannot be resolved by the traditional generalized Snell’s law, and can be implemented in the design of metasurfaces for moving applications.

Atmospheric brown carbon in China haze is dominated by secondary formation

Brown carbon (BrC) is a class of light-absorbing organic aerosols (OA) and has significant influence on atmospheric radiative forcing. However, the current limited understanding of the physicochemical properties of BrC restricts the accurate evaluation of its environmental effects. Here the optical characteristics and chemical composition of BrC during wintertime in the Yangtze River Delta (YRD) region, China were measured by using high-resolution aerosol mass spectrometry (HR-AMS) and UV–vis spectrometry. Our results showed that BrC in PM2.5 during the campaign was dominated by water-soluble organics, which consist of less oxidized oxygenated OA (LO-OOA), more oxidized oxygenated OA (MO-OOA), fossil fuel OA (FFOA) and biomass burning OA (BBOA). MO-OOA and BBOA were the strongest light absorbing BrC at 365 nm (Abs365), followed by LO-OOA and FFOA with a mass absorption coefficient (MAC) being 0.74 ± 0.04, 0.73 ± 0.03, 0.48 ± 0.04 and 0.39 ± 0.06 m2 g−1 during the campaign, respectively. In the low relative humidity (RH < 80 %) haze periods Abs365 of LO-OOA contributed to 44 % of the total light absorption at 365 nm, followed by MO-OOA (31 %), FFOA (21 %) and BBOA (4 %). In contrast, in the high-RH (RH > 80 %) haze periods Abs365 was dominated by MO-OOA, which accounted for 62 % of the total Abs365, followed by LO-OOA (17 %), BBOA (13 %) and FFOA (8 %). Chemical composition analysis further showed that LO-OOA and MO-OOA are produced from gas-phase photooxidation of VOCs and aerosol aqueous reactions, respectively, in which ammonia significantly enhanced the formation and light absorption of BrC in the high RH haze period. On average, >75 % of the total Abs365nm in the YRD region during the haze events was contributed by LO-OOA and MO-OOA, suggesting that atmospheric BrC in China haze periods is predominantly formed by secondary reactions.

A supported Ni2 dual-atoms site hollow urchin-like carbon catalyst for synergistic CO2 electroreduction

Dual-atoms catalysts (DACs), while inheriting the advantages of maximum atom utilization ratio and excellent selectivity of single-atom catalysts (SACs), can better enhance the catalytic activity through the synergy of adjacent atoms. Therefore, DACs are considered to be very potential catalysts for CO2 to CO conversion. Its catalytic activity is greatly influenced by the coordination environment and morphology. Here, hollow urchin-like NiNC catalysts (Ni-NC(HU)-x, x = 100, 50, 25, 0) were synthesized using urchin-like nickel particles as template. By adjusting the amount of additional nitrogen source, the percentage content of pyridinic-N was adjusted as well as further affecting the coordination environment. Among them, Ni-NC(HU)-50, which had the highest content of pyridinic-N, formed a dual-atoms coordination structure and had the best catalytic performance that the CO Faradaic efficiency (FECO) reached 97.2 % at −0.9 V vs. reversible hydrogen electrode (RHE) and sustained above 95 % within 50 h. In-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations showed that Ni-NC(HU)-50 exhibited the best performance of CO2 reduction reaction (CO2RR) by lowering the *COOH formation free energy barrier and its favorable dual desorption mechanism of *COL and *COB.