P-doped Graphene Research Articles

Anchoring Ru-Ru2P heterojunction on P-doped graphene for enhanced HER performances of water electrolysis

Highly active and stable electrocatalysts are highly desired for the hydrogen evolution reaction (HER) in water electrolysis. In this study, a ruthenium-ruthenium phosphide heterojunction (Ru-Ru2P) anchored on phosphorus-doped graphene (PCSG) was fabricated via a mild molten salt template method. The graphene was synthesized from discarded coconut shells sourced from Hainan. We found that the heterojunction structure could accelerate electron transfer, while the graphene provided more exposed active sites, significantly enhancing the HER activity of the catalyst. The catalyst prepared at 800 °C with 30mg of RuCl3 (Ru-Ru2P/2D-PCSG-800) exhibited low HER overpotentials of 31mV in alkaline and 57mV in acidic electrolytes at a current density of 10mAcm-2, respectively, which were comparable to those of commercial 20% Pt/C catalyst (36mV in alkaline and 40mV in acidic electrolytes). Moreover, the catalyst demonstrated high stability with no significant change in current density after 125hours of operation. Density functional theory calculations revealed that the Ru-Ru2P heterojunction could rearrange charge and modify the Ru d-band center, optimizing the adsorption energy of active ⁎H (|ΔG⁎H|) and breakage energy of ⁎H-OH bond (ΔGH2O).

Heterogeneous atoms mediated formation MnCo2S4/PNG heterostructures for high-performance supercapacitors

Transition metal sulfides are considered as potential electrode materials for high performance energy storage devices. However, structural instability during electrochemical reactions has seriously hindered their wide applications. In this study, we demonstrate that MnCo2S4/PNG (N- and P-doped graphene) composite constructed with hetero-atomic induction exhibits excellent morphological stability. Heterogeneous atoms doping on graphene can change its surface charge distribution. Under the induced effect of surface charge, the crystal growth and assembly process of MnCo2S4 nanostructure are changed as well, which leads to MnCo2S4 nanoparticles (NPs) uniformly anchored on the curled and folded PNG layer. In this case, it avoids the agglomeration of MnCo2S4 NPs, and thus increasing the specific surface area and pore volume of the composite, which is conducive to the full contact between the electrode and the electrolyte and therefore the rapid diffusion rate of the electrolyte ions at the interfaces. The obtained 1.4MnCo2S4/PNG material has a specific capacitance of 2465 F g−1 at 1 A g−1. In addition, the electrode possesses high conductivity, excellent rate performance and cyclic stability. The assembled 1.4MnCo2S4/PNG//PNG asymmetric supercapacitor yields an energy density of up to 65.1 Wh kg−1 under the power density of 800 W kg−1, showing excellent energy storage characteristics.

Effects of graphene doping and gas adsorption on the peak positions of graphene plasmon resonance and adsorbate infrared absorption

The peak positions of graphene plasmon resonance can be controlled to overlap with those of the infrared absorption spectra of gas molecules, allowing highly sensitive detection and identification by graphene nanoribbons. In this study, we investigate the adsorption of gas molecules, including SO2, SO3, H2S, and NH3, on graphene and characterize its effects on the relative positions of the two peaks using density functional theory and the finite difference time domain method. It is demonstrated that the binding energies are stronger, and the amounts of charge transfer are greater in the case of SO2 and SO3 adsorbed on n-doped graphene than in other cases. Electron acceptance by SO2 and SO3 adsorbates on n-doped graphene redshifts the graphene plasmon resonance peaks and their stretching and wagging infrared absorption peaks. However, the former is significantly further redshifted, leading to narrower peak-position-matching ribbon widths in n-doped graphene than in p-doped graphene. The amounts of charge transfer are relatively small regardless of the doping type in the case of NH3 and H2S, mitigating the doping-type dependence compared to SO2 and SO3. The wagging peaks of NH3 on n-doped graphene are shown to be further blueshifted than on p-doped graphene, rendering their peak-position-matching ribbon widths further closer to each other. These results suggest that the effects of doping and adsorption on the two types of peaks should be considered to optimize the performance of graphene plasmon-based gas sensing and identification.

Fabrication of Co- and P-Doped Laser-Induced Graphene for Use in Water Splitting Applications

Fabrication of Co- and P-Doped Laser-Induced Graphene for Use in Water Splitting Applications

Detection of type-Ⅱ diabetes using graphene-based biosensors

Diabetes is a global pandemic that increases the risk of various health complications, including heart attacks, renal failure, blindness, stroke, and peripheral neuropathy. Type-2 diabetes (T2D) results from an imbalance in lipid and glucose metabolism due to hostility to insulin action and insufficient insulin production response. Valine amino acid has been identified as a potential biomarker for T2D, but there have been no rigorous studies on its interaction with branch chain amino acids. In this study, we investigated the potential of graphene/modified graphene as a valine biosensor using density functional theory to examine the electronic properties and adsorption behaviour of graphene, Si-doped graphene (SiG), and P-doped graphene (PG). The adsorption of valine over the substrates was physisorption in nature, and the adsorption energies were in the order of SiG > G > PG. Density of states (DOS) and partial DOS calculations confirmed the molecule’s adsorption over the monolayers and indicated variations in the electronic properties. We also performed recovery time calculations to examine the reusability of the nano-surfaces as potential biosensors. Ultrafast recovery times were predicted for all three systems, with SiG showing the best results. Our study suggests that SiG could be used as a biosensor for valine, providing a real-time and efficient diagnostic tool for T2D.

Designing N, P-doped graphene surface-supported Mo single-atom catalysts for efficient conversion of nitrogen into ammonia: a computational guideline.

Tuning the surroundings of single-atom catalysts (SACs) has been recognized as a successful approach to enhance their electrocatalytic efficiency. In this study, we utilized density functional theory (DFT) computations to systematically investigate how the coordination environment influences the catalytic performance of individual molybdenum atoms for the nitrogen reduction reaction (NRR) to NH3. Upon comparing an extensive array of coordination combinations, Mo-based SACs were found to feature a distinctive N, P-dual coordination. Specifically, MoN3P1G demonstrates superior performance in the conversion of nitrogen into ammonia with an exceptionally low limiting potential (-0.64 V). This MoN3P1G catalyst preferably follows the distal pathway, with the initial hydrogenation step (*N2 → *NNH) being the rate-determining step. Additionally, MoN3P1G exhibits the ability to suppress competing H2 production, showcases high thermodynamic stability, and holds significant promise for experimental preparation. These findings not only contribute to diversifying the SAC family through localized coordination control but also present cost-effective strategies for enhancing sustainable NH3 production.

Engineering phosphorous doped graphene quantum dots decorated on graphene hydrogel as effective photocatalyst and high-current density electrocatalyst for seawater splitting

Designing metal-free catalyst with outstanding activity for both photocatalytic and electrocatalytic seawater splitting is highly demand and still remained challenge. This work demonstrates the synthesis of P-doped graphene quantum dots (PGQDs) containing different P-configuration bonding of PC3, PO4 and PO3 via synthesis temperature controlled simple hydrothermal process. Specifically, PGQDs having PC3-bonds (PGQD3) shows effectively tunable electronic structure, significant enhancing visible light absorption, then their hybrid composite with graphene hydrogel (PGQD3/GH) is prepared. The PGQD3/GH composite possesses excellent photocatalytic hydrogen production with yield of 20.47 mmol·g−1·h−1 in seawater splitting. Furthermore, the PGQD3/GH composite performs superior electrochemical activities of hydrogen evolution reaction (HER) toward seawater with an overpontetial of 41 mV at 10 mA·cm−2 as well as oxygen evolution reaction (OER) with 262 mV at 10 mA·cm−2. In seawater electrolysis cell, the PGQD3/GH composite delivers small overall voltage of 1.62 V to obtain high current density of 500 mA·cm−2 with excellent stability for 1000 h continuous operation, outperforming the commercial Pt/C and IrO2. This work demonstrates the role of PC3-bond in modulating the band gap and active site for photocatalytic and electrocatalytic seawater splitting reaction that may provide new idea for developing porous non-metal all-carbon catalyst for seawater splitting by both photocatalysis and electrocatalysis.

Investigation of supercapacitor electrode performances of phosphorus-doped graphene oxide electrodes in various deep eutectic solvents and symmetric supercapacitor application

A one-step preparation method of phosphorus-doped graphene oxide electrode (P-GOE) was used as electrode material for high-performance supercapacitors. Phosphorus-doped graphene oxides were synthesized on pencil graphite electrodes in one step with easy, cheap, and non-toxic chemicals by using the chronoamperometric process. Electrochemical analyses were carried out to examine the capacitive behavior of the electrodes in different deep eutectic solvents (DESs) (choline chloride:ethylene glycol (ChCl:EG), choline chloride:urea (ChCl:U), choline chloride:phenol (ChCl:Ph)). The electrolytes used make research valuable because these electrolytes were environmentally friendly, non-toxic, and inexpensive. Electrodes were analyzed by cyclic voltammetry at different scan rates, charge-discharge test at different current densities, 1000-cycle galvanostatic charge-discharge test, and electrochemical impedance spectroscopy (EIS). Structural and morphological properties of the electrodes were investigated by FTIR, XRD, SEM, BET, and XPS. As a result of the characterization and electrochemical analysis, it was seen that the phosphorus doping to the electrodes were carried out successfully. The maximum areal capacitances of phosphorus-doped graphene oxide electrodes were calculated to be 450 mF.cm−2, 140 mF.cm−2, and 400 mF.cm−2 in electrolytes for supercapacitor applications. In this study, high-performance P-doped graphene oxide electrodes were produced with an easy method using inexpensive and non-toxic solvents, providing an important contribution as environmentally friendly and sustainable electrode materials for supercapacitor applications.

Electronic and Magnetic Properties of FeCl3 Intercalated Bilayer Graphene

Graphene has gained significant attention since its discovery in 2004, and the modification of few-layer graphene provides a platform to tailor its physical and electronic properties. In this study, we employed unrestricted density functional theory (DFT) with the PBE+U functional to investigate the electronic and magnetic properties of FeCl3-intercalated bilayer graphene (BLG). Both in BLG and stage-2 intercalated graphite, a distinct localization of electrons on a specific Fe atom is evident, gaining approximately 0.245 electrons evaluated with Bader analysis, while the holes are delocalized within the graphene layers. This results in p-doped graphene, characterized by a shift of the Dirac cone by 0.74 eV for BLG and 0.70 eV for stage-2 intercalated graphite. Ferromagnetic ordering is observed within the plane of FeCl3-intercalated BLG, whereas the FeCl3 layers exhibit antiferromagnetic coupling in stage-2 intercalated graphite. The ferromagnetic nature and electronic structure of the FeCl3-intercalated BLG is retained under pressure.

Palladium-Phosphide-Modified Three-Dimensional Phospho-Doped Graphene Materials for Hydrogen Storage.

The development of efficient hydrogen storage materials is crucial for advancing hydrogen-based energy systems. In this study, we prepared a highly innovative palladium-phosphide-modified P-doped graphene hydrogen storage material with a three-dimensional configuration (3D Pd3P0.95/P-rGO) using a hydrothermal method followed by calcination. This 3D network hindering the stacking of graphene sheets provided channels for hydrogen diffusion to improve the hydrogen adsorption kinetics. Importantly, the construction of the three-dimensional palladium-phosphide-modified P-doped graphene hydrogen storage material improved the hydrogen absorption kinetics and mass transfer process. Furthermore, while acknowledging the limitations of primitive graphene as a medium in hydrogen storage, this study addressed the need for improved graphene-based materials and highlighted the significance of our research in exploring three-dimensional configurations. The hydrogen absorption rate of the material increased obviously in the first 2 h compared with two-dimensional sheets of Pd3P/P-rGO. Meanwhile, the corresponding 3D Pd3P0.95/P-rGO-500 sample, which was calcinated at 500 °C, achieved the optimal hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. According to molecular dynamics, the structure was thermodynamically stable, and the calculated adsorption energy of a single H2 molecule was -0.59 eV/H2, which was in the ideal range of hydrogen ad/desorption. These findings pave the way for the development of efficient hydrogen storage systems and advance the progress of hydrogen-based energy technologies.

Density functional theory study on direct dehydrogenation of propane catalyzed by N-, O-, and P-doped graphene catalysts

The density functional theory was used to calculate the reaction mechanism and selectivity of nonmetallic single-atom catalysts, such as N, O, and P, doped on graphene in the direct dehydrogenation of propane (PDH) . Our results show that the rate-controlling step in PDH varies with the doping atom. We also found that N, O, and P nonmetallic single-atom-doped graphene catalysts showed relatively low adsorption performance for propane and the active site was the C atom adjacent to N, O, and P, rather than the doped atom itself. Interestingly, for the O-doped graphene catalysts, which can reduce the reaction energy barrier by searching for multiple transition states, and the more transition states in the reaction path, the lower the energy barrier for the reaction rate-controlling step. Finally, the results show that the energy barrier of P-doped propane direct dehydrogenation reflecting the speed control step is the lowest, which is 44.32 kcal·mol−1, and the energy barrier of deep dehydrogenation is 53.08 kcal·mol−1; so it has good selectivity. Therefore, the P-doped graphene catalyst has a promising application as a nonmetallic catalyst for the direct PDH, which provides the possibility for the design of cheap and environmentally friendly catalysts.

A densely packed air-stable free-standing film with FeP nanoparticles@C@P-doped reduced graphene oxide for sodium-ion batteries.

Developing a facile strategy which enhances the structural stability and air/moisture stability of transition metal phosphides for practical applications is important but challenging. Herein, we designed a densely packed free-standing film consisting of carbon-coated FeP nanoparticles anchored on P-doped graphene (FeP@C@PG film) through solventless thermal decomposition and the roll-press method. Phytic acid serves a multifunctional role as both a phosphorus source to prepare ultrafine FeP nanoparticles and a protective layer to improve air stability along with hydrophobic graphene and maximize the utilization of phosphide. This structure can enhance electron/ion transport kinetics, allowing for full utilization of active materials, and buffer large volume expansions while preventing pulverization/aggregation during cycling. Noticeably, the densely packed structure can greatly enhance oxidation resistance by effectively blocking the penetration of air/moisture. Therefore, the FeP@C@PG film delivers a stable reversible capacity of 536.6 mA h g-1 after 1000 cycles at 1 A g-1 with good capacity retention, an excellent rate capability of 440.7 mA h g-1 at 5 A g-1, and excellent oxidation stability at 80 °C in air. Furthermore, a pouch-type full-cell exhibits excellent rate/cycling performance and bendability. This study provides a new direction for the rational design and practical applications of advanced P-based materials used in alkali metal-ion batteries.

First-principle calculation of electronic structure and optical properties of (P, Ga, P–Ga) doped graphene

Abstract First-principle calculations are used to study the electronic structures, electronic and optical properties of pure, phosphorus-doped, aluminum-doped, and phosphorus and aluminum co-doped graphene. The gap between the conduction band and valence band of intrinsic graphene is zero. However, when graphene is doped with P, Ga, and P–Ga, the gap in energy will be opened and to a different extent. In the three different doping results, the gap values between the conduction and valence bands of P, Ga, and P–Ga graphene are 0.11, 0.35, and 0.39 eV, respectively. When graphene is doped with P–Ga, more electrons (1.40 e) will be gained by carbon atoms compared to P-doped graphene (0.61 e), while fewer electrons (1.49 e) will be transferred to carbon atoms compared to Ga-doped graphene (1.75 e). After doping with P, Ga, and P–Ga, the overall intensity of the graphene absorption peak is weakened and more pronounced relative to the low-frequency peaks. This result can fully demonstrate that the band gap of the doped graphene system can be better tuned by adding phosphorus and gallium atoms.

Intrinsic activity and selectivity enhancement of single-atom Rh in syngas-to-C2 oxygenates by engineering the local coordination atom

Noble-metal Rh catalyst is promising for syngas conversion to C2 oxygenates, and the single-atom Rh catalysts hold promise to minimize Rh contents. In this work, a series of single-atom Rh catalysts anchored by the local coordination atom B, N and P-doped graphene (Rh-C4, Rh-N4, Rh-N3C1, Rh-N3P1 and Rh-N3B1) were theoretically predicted and verified by the related reported experiment to tune the selectivity and intrinsic activity of syngas conversion to C2 oxygenates. Here, DFT calculations and microkinetic modeling were implemented. The Rh-N3P1 catalyst was screened out to have excellent intrinsic activity, selectivity and thermal stability at 525 K, attributing to the synergistic active sites between the local coordination atoms (N/P) and Rh to provide abundant CHx monomer, followed by CO/CHO insertion to C2 oxygenates. The small positive charge and moderate d-band center of single-atom Rh in SACs are the essential attributes to improve intrinsic activity, namely, the precise local coordination of heteroatom N/P significantly regulates the electronic structure of single-atom Rh and further tunes catalytic performance. This study provides new insights and theoretical basis for engineering the local coordination atoms of carbon-based material supported metal SACs to tune catalytic performance and expanding their applications in the field of other systems.

Pd3P nanoparticles decorated P-doped graphene for high hydrogen storage capacity and stable hydrogen adsorption-desorption performance

The emergence of graphene provides a new research vector for the development of hydrogen storage materials. Herein, we firstly report a Pd3P nanoparticles decorated P-doped graphene material by a facile pyrolysis method for hydrogen storage. The size of Pd3P particles is distributed on the graphene surface uniformly in the range of 20–30 nm. It has a high gravimetric density of hydrogen storage of 3.66 wt% at mild conditions (298 K, 4 MPa). When the temperature drops to 253 K, the hydrogen storage capacity increases to 3.94 wt%; whereas at the pressure of 5.5 MPa and 298 K, the hydrogen storage capacity is up to 4.7 wt%. The Pd3P nanoparticles decorated P-doped graphene has both physical and chemical hydrogen adsorption mechanisms during the hydrogen storage process. The hydride produced by chemical adsorption remains stable even at 498 K, which is the main reason for 1.03 wt% of the capacity loss during the hydrogen adsorption-desorption cycle. After 4 cycles of hydrogen adsorption-desorption at 298 K and 4 MPa, the effective hydrogen storage capacity of Pd3P nanoparticles decorated P-doped graphene is 2.63 wt%, and the Pd3P nanoparticles on the graphene are evenly distributed with stable structure after cycles, which is conducive to the realization of reversible hydrogen storage.

Can P- and Oxidized P-doped Graphene be a Good Anode for Na-Ion Batteries?: A First-Principles Assessment

Sodium ion batteries (NIBs) become an important emerging alternative to lithium ion batteries (LIBs) because of low cost and suitability for large-scale applications. However, optimizing anodes in NIBs is still a challenge. In this paper, we investigated the possibility of using P- and oxidized P-doped graphene as an anode in NIBs. We reveal important fundamental properties of sodium adsorption on P- and oxidized P-doped graphene by employing first principles calculations. Our results suggest that Na adsorption on the single side of substrate followed by on the other side is the preferred configuration with high Na capacity of 511 mAh g−1. Na is predicted to migrate with a low diffusion barrier near the protrudent P and OP on the substrate. Although Na has to cross an elevated diffusion barrier to escape from the most stable site interacting with the P and OP, this can be significantly mitigated by increasing the adsorbed Na concentration. Our calculations also demonstrate the structures mostly maintain the metallic properties thus shows high electron mobility upon a wide range of sodiation level. Our findings indicate that P- and oxidized P-doping of graphene anodes can be a promising route toward increasing the overall performance of NIBs for practical application.

Mechanism of ozone adsorption and activation on B-, N-, P-, and Si-doped graphene: A DFT study

• Detailed evolution mechanism of O 3 into ROS on the doped graphene was revealed. • O ads produced from O 3 decomposition was a vital intermediate to generate other ROS. • Types and efficiency of the formed ROS from O ads depended on the doped heteroatoms. • CDD was a useful descriptor for carbonaceous catalyst design based on QSAR model. The detailed evolution mechanism of O 3 into Reactive oxygen species (ROS) is of paramount importance but remains elusive in catalytic ozonation. Herein, we report a density functional theory study to comprehensively reveal the specific evolution processes of O 3 into ROS on the B-, N-, P-, and Si-doped graphene, including the adsorption, decomposition and ROS generation. In contrast to some previous reports that O 3 would directly decompose into effective ROS on catalysts, our results indicate that after O 3 adsorption, the decomposition products are ground state O 2 and the adsorbed oxygen species (O ads ). The O ads is more likely to act as a crucial intermediate for generating other ROS instead of directly attacking the organics. The type of the ROS and generation efficiency vary with the doped heteroatoms, and the heteroatoms of B, P and Si, or the neighboring C of N, would serve as active sites for O 3 adsorption and decomposition. The N- and P-doped graphene are predicted to have the superior performance in ROS generation and catalytic stability. Finally, twenty representative descriptors were adopted to build the quantitative structure–activity relationship (QSAR) with the activation energy barrier of O 3 decomposition. The result indicates that condensed dual descriptor (CDD) could be useful for preliminarily selecting the modified graphene catalysts, since it shows a very good linear relation with the activation energy barrier. This contribution provides an alternative way to gain fundamental insights into the mechanism of catalytic ozonation at the molecular level, and could be helpful for designing more-efficient catalysts in environmental remediation.

One-step electrodeposition synthesis of FeCoNiP nanoparticles/Vertical P-doped graphene on Cu substrate as high-activity electrocatalyst for overall water splitting in a wide pH range

FeCoNiP nanoparticles integrated on vertical P-doped graphene is facilely fabricated on Cu foil (FeCoNiP/PVG/Cu) by one-step electrodeposition as electrocatalyst toward overall water splitting in a wide pH range. The FeCoNiP/PVG/Cu electrocatalyst exhibits low overpotentials (115 and 223 mV) at 10 mA [Formula: see text] cm[Formula: see text] and low Tafel slopes (70 and 76 mV [Formula: see text] dec[Formula: see text] toward hydrogen evolution reaction in 1.0 M KOH and 0.5 M H2SO4, respectively. At the same time, the FeCoNiP/PVG/Cu electrocatalyst exhibits a remarkable activity with overpotential of 361 mV at 50 mA [Formula: see text] cm[Formula: see text] and Tafel slope of 96 mV [Formula: see text] dec[Formula: see text] in 1.0 M KOH toward oxygen evolution reaction, which is even comparable with the noble IrO2 electrocatalyst (370 mV and 80 mV [Formula: see text] dec[Formula: see text]. FeCoNiP/PVG/Cu electrocatalyst also displays a remarkable electrochemical durability to toward HER in both alkaline and acid solutions for at least 15 h, toward OER in alkaline solution for at least 13 h. This work contributes to the research of designing non-noble earth-abundant electrocatalyst with high property in a wide pH range for overall water splitting, thus pushing the development of industrial utilization of water splitting.

Optimization of the Urea Removal in a Wearable Dialysis Device Using Nitrogen-Doped and Phosphorus-Doped Graphene.

Dialysis has been recognized as an essential treatment for end-stage renal disease (ESRD). This therapy, however, suffers from several limitations leading to numerous complications in the patients. As dialysis cannot completely substitute healthy kidney functions, the health condition of an ESRD patient is ultimately affected. Wearable artificial kidney (WAK) can resolve the restrictions of blood purification by the dialysis method. However, absorbing large amounts of urea produced in the body is one of the main challenges of these WAK and overcoming this is necessary to improve both functionality and footprint of the device. This study investigates the adsorption capabilities of N- and P-doped graphene nanosorbents for the first time by using molecular dynamic simulation. Urea removal on carbon nanosheets was simulated with different percentages of phosphorus and nitrogen dopants along with the pristine graphene. Specifically, the effects of interaction energy, adsorption percentage, gyration radius, hydrogen bonding, and other molecular dynamic analyses on urea removal were also investigated. The results from this study match well with the existing research, demonstrating the accuracy of the model. The results further suggest that graphene nanosheets doped by 10% nitrogen are likely the most effective in removing urea given that it is associated with the maximum radial distribution function (RDF), the maximum reduction in gyration radius, a high number of hydrogen bonds, and the most negative adsorption energy. This molecular study offers attractive suggestions for the novel adsorbents of artificial kidney devices and paves the way for the development of novel and enhanced urea adsorbents.

P-Doped graphene-C60 nanocomposite: a donor-acceptor complex with a P-C dative bond.

Phosphorous-doped graphene can form a covalent dative bond with the electron acceptor, C60 molecule. On the other hand, C60 on graphene and N-doped graphene surfaces can only form vdW complexes. State-of-the-art quantum-chemical techniques have been used to characterise the nature of the P-C dative bond. A considerable amount of charge transfer from the P-Gr surface to C60 has been observed. This complex formation may enable enhancement in the optical limiting response with potential application in energy harvesting. The stability of the P-C dative bond has been assessed using DFT-D molecular dynamics simulations at 300 K for 10 ps.