Water Adsorption Energy Research Articles

Computational insights into graphene-based materials for arsenic removal from wastewater: a hybrid quantum mechanical study

The discharge of industrial wastewater, particularly from chemical and mining industries, poses significant threats to the environment, public health, and safety due to high concentrations of pollutants leading to serious illnesses and the loss of aquatic life. It is therefore essential and urgent to devise measures for mitigating these threats. To advance the understanding of graphene membranes for Arsenic (As) removal from wastewater, this research investigates As adsorption and its relative selectivity on graphene-based materials using computational approaches. Our study employed hybrid quantum mechanical calculations for energy and geometry optimization to explore As adsorption on pristine graphene membrane surfaces in vacuum and aqueous environments. We assessed the effect of different adsorption sites on the surface which includes the top (T), bridge (B), and hollow (H) sites across the edge (E) and center (C) regions of the absorbent surface, to identify the optimal site/mode of adsorption. Our results demonstrate that the edge sites are the most effective for adsorption, exhibiting strong adsorption energies in both vacuum (− 1.98 eV) and aqueous environments (− 1.97 eV). These values are significantly higher than the adsorption energies for water on the surface, which range from − 0.25 to − 0.26 eV. Geometrical analyses confirmed the bridge edge sites as the most preferred adsorption configuration. Our findings not only advance upon existing computational approaches for designing efficient adsorbents but also provide deeper insights into the adsorption mechanisms on graphene-based materials. Unlike previous studies, which focused primarily on experimental or theoretical aspects in isolation, this work integrates computational and theoretical approaches to optimize adsorption processes at the molecular level. By investigating membrane properties for As removal, this research offers a novel pathway for developing advanced adsorbents, addressing critical challenges in environmental remediation with greater precision and efficiency.Graphical

On the Relationship between Water Adsorption and Surface Chemistry in Soda-lime Silicate Glasses.

Understanding how the surface structure affects the bioactivity and degradation rate of the glass is one of the primary challenges in developing new bioactive materials. Here, classical and reactive molecular dynamics simulations are used to investigate the relationship between local surface chemistry and local adsorption energies of water on three soda-lime silicate glasses. The compositions of the glasses, (SiO2)65-x(CaO)35(Na2O)x with x=5, 10, and 15, were chosen for their bioactive properties. Analysis of the glass surface structure, compared to the bulk structure, showed that the surface is rich in modifiers and non-bridging oxygen atoms, which were correlated with local adsorption energies. The reactivity of the glasses is found to increase with higher Na2O content, attributed to elevated Na cations and undercoordinated species at the glass surfaces. The current work provides insights into the relationship between the surface structure, chemistry, and properties in these bioactive glasses and offers a step toward their rational design.

Ab-Initio study of water molecule adsorption on monoclinic Scheelite-Type BiVO4 surfaces

Herein, we present a study on the adsorption of one water molecule (bonded to either Bi or V sites) and two water molecules (bonded to both Bi and V sites) onto seven low-index surfaces (001), (010), (011), (100), (101), (110), and (111) as well as one high-index surface (211) of a monoclinic scheelite-type BiVO4 crystal structure using ab initio calculations. By predicting the adsorption energies for different facets, we find that water adsorption is more likely to occur on Bi sites. However, for the (001) and (211) surfaces, water adsorption is more likely on the V sites. Furthermore, we find that the studied low-index facets can be grouped into four distinct categories. Facets within the same group exhibit similar water adsorption energies. These groups are ((001)), ((010), (100)), ((110)), and ((011), (101), (111)). For low-index surfaces, favorable adsorption occurs on the (001) surface on the V sites.

Navigating Alkaline Hydrogen Evolution Reaction Descriptors for Electrocatalyst Design

The quest for efficient green hydrogen production through Alkaline Water Electrolysis (AWE) is a critical aspect of the clean energy transition. The hydrogen evolution reaction (HER) in alkaline media is central to this process, with the performance of electrocatalysts being a determining factor for overall efficiency. Theoretical studies using energy-based descriptors are essential for designing high-performance alkaline HER electrocatalysts. This review summarizes various descriptors, including water adsorption energy, water dissociation barrier, and Gibbs free energy changes of hydrogen and hydroxyl adsorption. Examples of how to apply these descriptors to identify the active site of materials and better design high-performance alkaline HER electrocatalysts are provided, highlighting the previously underappreciated role of hydroxyl adsorption-free energy changes. As research progresses, integrating these descriptors with experimental data will be paramount in advancing AWE technology for sustainable hydrogen production.

Molecular picture of electric double layers with weakly adsorbed water.

Water adsorption energy, Eads, is a key physical quantity in sustainable chemical technologies such as (photo)electrocatalytic water splitting, water desalination, and water harvesting. In many of these applications, the electrode surface is operated outside the point (potential) of zero charge, which attracts counter-ions to form the electric double layer and controls the surface properties. Here, by applying density functional theory-based finite-field molecular dynamics simulations, we have studied the effect of water adsorption energy Eads on surface acidity and the Helmholtz capacitance of BiVO4 as an example of metal oxide electrodes with weakly chemisorbed water. This allows us to establish the effect of Eads on the coordination number, the H-bond network, and the orientation of chemisorbed water by comparing an oxide series composed of BiVO4, TiO2, and SnO2. In particular, it is found that a positive correlation exists between the degree of asymmetry ΔCH in the Helmholtz capacitance and the strength of Eads. This correlation is verified and extended further to graphene-like systems with physisorbed water, where the electric double layers (EDLs) are controlled by electronic charge rather than proton charge as in the oxide series. Therefore, this work reveals a general relationship between water adsorption energy Eads and EDLs, which is relevant to both electrochemical reactivity and the electrowetting of aqueous interfaces.

Metal-water interface formation: Thermodynamics from abinitio molecular dynamics simulations.

Metal-water interfaces are central to many electrochemical, (electro)catalytic, and materials science processes and systems. However, our current understanding of their thermodynamic properties is limited by the scarcity of accurate experimental and computational data and procedures. In this work, thermodynamic quantities for metal-water interface formation are computed for a range of FCC(111) surfaces (Pd, Pt, Au, Ag, Rh, and PdAu) through extensive density functional theory based molecular dynamics and the two-phase entropy model. We show that metal-water interface formation is thermodynamically favorable and that most metal surfaces studied in this work are completely wettable, i.e., have contact angles of zero. Interfacial water has higher entropy than bulk water due to the increased population of low-frequency translational modes. The entropic contributions also correlate with the orientational water density, and the highest solvation entropies are observed for interfaces with a moderately ordered first water layer; the entropic contributions account for up to ∼25% of the formation free energy. Water adsorption energy correlates with the water orientation and structure and is found to be a good descriptor of the internal energy part of the interface formation free energy, but it alone cannot satisfactorily explain the interfacial thermodynamics; the interface formation is driven by the competition between energetic and entropic contributions. The obtained results and insight can be used to develop, parameterize, and benchmark theoretical and computational methods for studying metal-water interfaces. Overall, our study yields benchmark-quality data and fundamental insight into the thermodynamic forces driving metal-water interface formation.

Controlled synthesis of M doped NiMoO4 (M = Co, Cu and Fe) for urea, freshwater and seawater oxidation reaction

Electrocatalytic splitting of urea or seawater for hydrogen production has become one of the most promising methods. In this paper, different foreign ions M (M = Co, Cu and Fe) are introduced into this NiMoO4 material by hydrothermal and impregnation methods. Their electrocatalytic properties were investigated in different electrolytes, such as urea, pure water and seawater. What is noteworthy is that the Co-NiMoO4/NF electrode exhibited superior urea oxidation properties (1.32 V @ 10 mA cm−2). The different reaction mechanisms result in the superior water oxidation performance of this Fe3+-NiMoO4/NF material. What is noteworthy is that the durability of the material needs to be improved. The promoted performance is attributed to rapid electron transfer and improved electrical conductivity. Density functional theory (DFT) also shows that this Fe-NiMoO4/NF electrode presents optimal water adsorption energy and improved electrical conductivity, thus improving the catalytic activity of the material because of introduction of Fe. The work provides novel views for the design of environmentally friendly and inexpensive multifunctional catalysts for urea, freshwater and seawater splitting reaction.

Heat and mass transfer analysis of desiccant-coated heat exchanger with desiccants and metal-organic framework for bus air conditioning applications

Desiccant-coated heat exchangers (DCHEs) in air conditioning offer advantages like independent temperature and humidity control, reduced energy consumption, and high performance. However, the availability of desiccants with high water adsorption and low thermal energy requirements is limited. The present study proposes that aluminum fumarate (Al-Fum) MOF-coated heat exchangers will outperform conventional desiccants, especially at low regeneration temperatures (around 50°C). In order to evaluate this hypothesis, the performance of DCHEs was evaluated with a validated analytical model for different solid desiccant coatings: silica gel, zeolite, and Al-Fum MOF. Water vapor sorption characteristics, heat and mass transfer, and adsorption and desorption capacities were determined. The results showed that the Al-Fum MOF-coated heat exchanger outperformed silica gel and zeolite at low regeneration temperatures under adiabatic conditions. The MOF exhibited superior water uptake capacity (0.39 g/g) between 20% and 80% RH compared to the other studied conventional desiccants. Moreover, the MOF achieved the lowest outlet air temperature. At 19.5 g/kgda, the MOF demonstrated higher adsorption rates (4 % and 0.3 %) than zeolite and silica gel. These findings highlight the potential of Al-Fum MOFs as energy-efficient solutions for controlling indoor air humidity, particularly for latent-sensible heat separation systems with conventional vapor compression bus air-conditioning systems.

Mn-doped nickel-copper phosphides as oxygen evolution reaction electrocatalyst in alkaline seawater solution

Compared with traditional water electrolysis, electrolysis of seawater has larger resources and a brighter future. However, seawater contains more elements that have greater corrosive effects on electrodes; especially chloride ions (seawater contains more chloride ions) have the greatest impact. The existence of the corrosion problem creates greater difficulties in electrolyzing seawater, further limiting the efficiency of the electrocatalyst for electrolysis of seawater. In this paper, we report a Mn-doped Ni2P/Cu3P as an environmentally friendly monofunctional electrode for seawater electrolysis, which was made by a simple hydrothermal phosphatization operation method. The experimental results show that Mn-doped Ni2P/Cu3P presents overpotential of only 161 mV for oxygen evolution reaction (OER) at iR compensation of 90 and a current density of 10 mA cm−2. It has a small Tafel slope (25.15 mV dec−1) and a large capacitance (9.58 mF cm−2 on 1 × 1 nickel foam), which exceeds most reported oxygen evolution activities of non-precious metal-based electrocatalysts for electrolysis of alkaline seawater. The performance of Ni2P/Cu3P was probably significantly enhanced due to Mn doping by some characterization means. Through Density functional theory (DFT) analysis, it is known that the doping of Mn gives a large enhancement in the adsorption energy of water when Ni2P/Cu3P is electrolyzed with seawater. This paper provides train of thought for the exploration of excellent electrocatalysts for electrolysis of alkaline seawater.

Fabrication and characterization of a novel multilayer heterojunction Si3N4-PbO2 nanocomposite electrode and its application on electrocatalysis degradation of sulfathiazole

To lengthen the lifetime and extend the potential commercial applications of lead dioxide electrode, herein, a novel multilayer heterojunction Ti/ SnO2-Sb2O3/ graphene oxide/ carbon nanotube/ Si3N4-PbO2 electrode (Si3N4-PbO2 electrode) was fabricated by co-electrodeposition process that doping Si3N4 nanoparticles in eletroplating solution. Various spectroscopic and microscopic techniques, including scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were employed to characterize the surface of the fabricated electrode. The EDS analysis confirmed the successful attachment of 5.49 %wt Si and 2.46 %wt N elements from Si3N4 nanoparticles onto the PbO2 surface, while the XRD results indicated a shift in the preferred orientation of PbO2 grains from β(110) to β(101). The water adsorption energy and ·OH desorption energy in the electrocatalysis process were determined to be 0.71 eV and 0.241 eV through theoretical calculating. Subsequently, the Si3N4-PbO2 electrode was employed as an anode for the electrocatalytic degradation of sulfathiazole-simulated wastewater and real sulfonamides wastewater. Under optimized conditions determined via response surface methodology (RSM), the COD degradation efficiency reached 69.37 % for sulfathiazole and 62.35 % for real sulfonamides wastewater. The final COD concentration of the real sulfonamides wastewater was reduced to 77.05 mg/L, under the national urban sewage discharge standard. Finally, the degradation mechanism and pathway of sulfathiazole has been arranged based on the electron spin resonance (ESR), cyclic voltammetry (CV), while the intermediates were detected by Gas Chromatography-Mass Spectrometer (GC-MS) and the reactive sites of sulfathiazole were predicted by using Fukui function.

Efficacious destruction of typical aromatic hydrocarbons over CoMn/Ni foam monolithic catalysts with boosted activity and water resistance

Developing cost-effective monolith catalyst with superior low-temperature activity is critical for oxidative efficacious removal of industrial volatile organic compounds (VOCs). However, the complexity of the industrial flue gas conditions demands the need for high moisture tolerance, which is challenging. Herein, CoMn–Metal Organic Framework (CoMn–MOF) was in situ grown on Ni foam (NiF) at room temperature to synthesize the cost-effective monolith catalyst. The optimized catalyst, Co1Mn1/NiF, exhibited excellent performance in toluene oxidation (T90 = 239 °C) due to the substitution of manganese into the cobalt lattice. This substitution weakened the Co–O bond strength, creating more oxygen vacancies and increasing the active oxygen species content. Additionally, experimentally and computationally evidence revealed that the mutual inhibiting effect of three typical aromatic hydrocarbons (benzene, toluene and m–xylene) over the Co1Mn1/NiF catalyst was attributed to the competitive adsorption occurring on the active site. Furthermore, the Co1Mn1/NiF catalyst also presents outstanding water resistance, particularly at a concentration of 3 vol%, where the activity is even enhanced. This was attributed to the lower water adsorption and dissociation energy derived from the interaction between the bimetals. Results demonstrate that the dissociation of water vapor enables more reactive oxygen species to participate in the reaction which reduces the formation of intermediates and facilitates the reaction. This investigation provides new insights into the preparation of oxygen vacancy–rich monolith catalysts with high water resistance for practical applications.

Ordered PtNiTiZrHf nanoparticles on carbon nanotubes catalyze hydrogen evolution reaction with high activity and durability

With the scarcity of the earth's natural resources, hydrogen production from electrolyzing water is seen as an alternative energy source. Although platinum (Pt) is an advanced catalyst for hydrogen evolution reaction (HER), its application is limited by high cost and limited electrocatalytic performance. In this article, the five-element alloy nanoparticles are successfully synthesized on carbon nanotubes (CNT) by employing liquid-phase reduction and gas-phase sintering to reduce Pt utilization and improve catalytic performance. For comparison, a series of ordered and disordered (PtNi)x(TiZrHf)100-x/CNT catalysts are obtained. Results show that the ordered samples have more excellent HER catalytic performance and stability than disordered samples in 0.5 M H2SO4 and 1 M KOH electrolytes. In particular, when the electrolyte is acidic, the overpotentials of ordered (PtNi)55(TiZrHf)45/CNT at 10 and 100 mA cm−2 are 11 and 52 mV, with low Tafel slope of 37.73 mV dec−1. At 10 mA cm−2, the stabilization time can reach 58 h, which is much better than commercial Pt/C (20 wt.%). Density functional theory (DFT) calculation shows that ordered (PtNi)55(TiZrHf)45/CNT has lower hydrogen adsorption energy and activated water adsorption energy than disordered one, indicating better performance in both acidic and alkaline electrolytes. It is mainly attributed to the electronic coupling effect after ordering that makes the overall D-band center decrease. This work presents a cost-effective approach to optimize the structural design for acid-base HER electrocatalysts.

Regulation of the d-band center of metal–organic frameworks for energy-saving hydrogen generation coupled with selective glycerol oxidation

The hybrid electrolyzer coupled glycerol oxidation (GOR) with hydrogen evolution reaction (HER) is fascinating to simultaneously generate H2 and high value-added chemicals with low energy input, yet facing a challenge. Herein, Cu-based metal-organic frameworks (Cu-MOFs) are reported as model catalysts for both HER and GOR through doping of atomically dispersed precious and nonprecious metals. Remarkably, the HER activity of Ru-doped Cu-MOF outperformed a Pt/C catalyst, with its Faradaic efficiency for formate formation at 90% at a low potential of 1.40 V. Furthermore, the hybrid electrolyzer only needed 1.36 V to achieve 10 mA cm-2, 340 mV lower than that for splitting pure water. Theoretical calculations demonstrated that electronic interactions between the host and guest (doped) metals shifted downward the d-band centers (εd) of MOFs. This consequently lowered water adsorption and dissociation energy barriers and optimized hydrogen adsorption energy, leading to significantly enhanced HER activities. Meanwhile, the downshift of εd centers reduced energy barriers for rate-limiting step and the formation energy of OH*, synergistically enhancing the activity of MOFs for GOR. These findings offered an effective means for simultaneous productions of hydrogen fuel and high value-added chemicals using one hybrid electrolyzer with low energy input.

Controlled synthesis of Co3O4@CoP heterostructured nanoarrays as efficient electrocatalysts in alkaline seawater and urea

How to prepare clean energy has always been a problem to be solved by the modern green chemical industry. Compared with the electrolysis of water to produce hydrogen, electrolysis of seawater for raw material requirements are lower and more widely used. However, the lacks of maturity of the technology, the high cost and the generation of harmful gases such as chlorine in the electrocatalytic process have hindered the development of this process. This study demonstrates a construction of heterogeneous structure based on Co ions as an efficient multifunctional catalyst for overall seawater splitting and urea oxidation. This hybrid structure can combine nanosheets and nanowires, thus exposing the catalyst to more active sites and shortening the ion diffusion path. Comparing the hybrid structure with the single structure, Co3O4@CoP exhibits excellent multifunctional catalytic activity in alkaline seawater and urea. In the oxygen evolution reaction, the working potential is only 1.60 V and 1.70 V at a current density of 50 mA/cm2 and 100 mA/cm2. And in the hydrogen evolution reaction, the working potential was only −0.16 V at a current density of −10 mA/cm2, demonstrating excellent bifunctional activity. On this basis, the catalyst also demonstrated excellent activity for urea oxidation reaction in alkaline environment, with an operating potential of only 1.28 V at a current density of 10 mA/cm2. And the durability of this catalyst is good, it can keep 5 mA/cm2 for 12 h under the constant voltage of 1.45 V, but the initial potential falls off too fast, and there is a decline in performance, which is closely related to the corrosion of Cl- present in seawater. It was shown by density functional theory (DFT) that hierarchical nanostructures can increase the transfer rate of reaction intermediates and the water adsorption energy. At the end of this study, by comparing single nanostructures with hybrid nanostructures, it can be reasonably conjectured that the accompanying increase in the number the heterostructure is resistant to Cl- corrosion in seawater.

Characterization of moisture migration and diffusion in two types of tobacco biomass during the dehydration process by the TG-NMR analysis.

The tobacco waste generated from the tobacco agriculture and industry, including the discarded stem and leaf, often needs dehydration pretreatment before thermal conversion utilization. In order to study the water activity and migration of tobacco waste during the pretreatment process, TG-NMR (Thermogravimetric Nuclear Magnetic Resonance) was used to obtain the drying curves and LF-NMR (Low Field Nuclear Magnetic Resonance) T2 inversion spectrum at each stage of tobacco drying. Meanwhile, the variation pattern of pore distribution during the dehydration process of two types of tobacco waste has been obtained. Combined with the pore distribution changes, a possible spatial migration mode of water was proposed. The change of adsorption energy of water during tobacco drying was calculated, and verified the above hypothesis. This study results provide reference for the optimization of dehydration pretreatment process for different tobacco waste in order to reduce energy consumption during recycling of tobacco biomass.

Electrochemical Nitrate Reduction Catalyzed by Two-Dimensional Transition Metal Borides.

We investigated 2D transition metal borides (MBenes) for the efficient conversion of nitrate to ammonia. MBenes have been previously shown to bind oxygen with extraordinary strength, which should translate toward selective adsorption of nitrate in aqueous media. Using Density Functional Theory, we screened MBenes by computing their nitrate and water adsorption energies, seeking materials with strong nitrate binding and weak water binding. We identified MnB, CrB, and VB as the best materials for selective nitrate adsorption and proceeded by computing their free energies for generating ammonia. Of the three candidates, CrB requires the lowest overpotential, making it the best candidate. To further decrease the overpotential, we doped the CrB MBene with secondary transition metals and found the addition of Mn to the active site further reduced the overpotential. We then computed the reaction mechanism grand canonically to observe the effect of applied potential on the free energy landscape.

Ultrafine Iridium Nanoparticles Anchored on Co-Based Metal-Organic Framework Nanosheets for Robust Hydrogen Evolution in Alkaline Media.

A highly promising electrocatalyst has been designed and prepared for the hydrogen evolution reaction (HER). This involves incorporating well-dispersed Ir nanoparticles into a cobalt-based metal-organic framework known as Co-BPDC [Co(bpdc)(H2O)2, BPDC: 4,4'-biphenyldicarboxylic acid]. Ir@Co-BPDC demonstrates exceptional HER activity in alkaline media, surpassing both commercial Pt/C and recent noble-metal catalysts. Theoretical results indicate that electron redistribution, induced by interfacial bonds, optimizes the adsorption energy of water and hydrogen, thereby enhancing our understanding of the superior properties of Ir@Co-BPDC for HER.

A heterostructure of interlayer-expanded 1T phase MoS2 and spherical MoO2 for efficient and stable hydrogen evolution

The inferior hydrogen evolution reaction (HER) catalytic performance of MoS2 can be attributed to its small edge ratio, large inert substrate surface, and poor electrical conductivity, while the multiple strategies are expected to be employed simultaneously to modulate the electronic structure of MoS2 and yield catalysts with superior HER catalytic performance. Here, we report a MoS2 containing a 1 T phase with expanded layer spacing and construct it as a heterostructured material with MoO2 (MoO2 @E-MoS2). Specifically, the presence of the 1 T phase and expanded layer structure of MoS2 can enhance electrode conductivity, increase active site exposure, promote H2O adsorption, and optimize the Gibbs-free energy of hydrogen. The constructed heterostructure can modulate the electronic structure of the catalyst, enhance electron transfer at the interface, elevate water adsorption energy, and reduce the hydrogen reaction energy barrier. Moreover, density functional theory calculations indicate that the S site of MoS2 in this catalyst exhibits a higher affinity for H2O adsorption, while the Mo site demonstrates a greater capacity for H* adsorption/desorption. Ultimately, MoO2 @E-MoS2 shows low overpotentials of 93 and 99 mV at a current density of 10 mA cm−2, as well as exceptional long-term stabilities exceeding 70 and 130 h at current densities ranging from 10 to 30 mA cm−2 in acidic and alkaline media, respectively.

Iron and phosphorus dual-doped NiMoO4 with nanorod structure as efficient oxygen evolution catalyst in alkaline seawater

Hydrogen production by electrolysis of seawater is more in line with the new era of green chemistry than electrolysis of freshwater, but the high cost and the accompanying chlorine evolution hinder the development of the process. In this study, the growth of transition metal elements Fe as well as P double-doped NiMoO4 with nanorod-like nanostructures on Ni foam (Fe/P–NiMoO4@NF) is feasible. The optimized Fe/P–NiMoO4@NF material exposes more active sites, which exhibits excellent oxygen evolution reaction (OER) activity in alkaline seawater. At a current density of 10 mA cm−2, the operating potential is only 1.35 V and operating potential of 1.54 V at 100 mA cm−2 is obtained with Tafel slopes as small as 13.16 mV dec−1. The enhanced activity is attributed to the exposure of more active sites and faster charge transfer due to double doping of Fe and P. And the catalyst exhibited relatively good durability, which could be maintained at 50 mA cm−2 for 24 h at a constant voltage of 1.60 V without IR-compensation. The experiment result shows that the doped P smoothly covers on the surface the catalyst, making the surface metal compound on the nickel foam is resistant to seawater corrosion. Density Functional Theory (DFT) shows that double doping of Fe and P can increase the electron transfer rate and enhance the adsorption energy of water. This work provides a new and simple double doping strategy for the development of high-performance catalysts with controllable morphology for seawater splitting.

An investigation of the effects of porosity and N-defects of 2D CxNy membranes on the wettability behavior and separation capability of water and oil mixtures

In this study, three different structures of two dimentional (2D) CxNy were investigated experimentally and theoretically to determine their wettability behavior and separation capability based on their porosity, surface defect structure, and surface energy. The C3N, C1N1, and graphitic-C3N4 (g-C3N4) were synthesized and coated on stainless steel mesh. Wettability characteristics of the C3N, C1N1, and g-C3N4-coated mesh showed hydrophobic/oleophilic, hydrophilic/ underwater super-oleophobic, and super-hydrophilic/underwater super-oleophobic, respectively. The experimental results showed that the best performance of C3N with the highest surface area was obsereved in oil removal and the best performance of g-C3N4 with the highest pyridinic-N/pyrrolic-N XPS peak-area ratio was observed in water removal. Since electrostatic interaction plays an important role in water-removing state, increasing the number of pyridinic-N increases the electrostatic potential of water with the surface during water removal. Based on surface energy calculations, the highest dispersed surface energy is found in C3N, whereas the strongest polar component is found in g-C3N4, confirming their hydrophobic and hydrophilic wettability, respectively. Density functional theory investigations confirmed the higher hydrophilicity of g-C3N4 due to its non-uniform electron density distribution. The adsorption energies of water and decalin molecules are proportional to the amounts of charge transfer between porous substrates and adsorbents.