Rational design of free-standing 3D Cu-doped NiS@Ni2P/NF nanosheet arrays for hydrogen evolution reaction

Li, Hui; Gao, Guanyun; Zhao, Huimin; Wang, Wensi; Yang, Yu; Du, Yunmei; Li, Shaoxiang; Liu, Yanru; Wang, Lei

doi:10.1016/j.ijhydene.2021.07.059

Cited by 10 publications

(6 citation statements)

References 57 publications

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“…Thus, the high HER activity of TPOP could be observed because of the low charge-transfer resistance and ease of charge transfer at the electrode−electrolyte interface. 34 Furthermore, the high HER activity of TPOP is attributed to its electronic structure and the presence of N-rich moieties within the framework. A chronoamperometric (CA) study with the TPOP@12 electrode was performed at −0.16 V vs RHE, and the almost invariable current density suggested the reliable lifetime of the catalyst (Figure S16).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The Nyquist plot and subsequent equivalent circuit fitting ( R || C ) provided a minimum R ct value of 3.2 Ω for TPOP@12 as compared to MPOP@12 and NF, showing better charge transfer across the electrode–electrolyte junction (Figure d). Thus, the high HER activity of TPOP could be observed because of the low charge-transfer resistance and ease of charge transfer at the electrode–electrolyte interface . Furthermore, the high HER activity of TPOP is attributed to its electronic structure and the presence of N-rich moieties within the framework.…”

Section: Resultsmentioning

confidence: 99%

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Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Chaudhary,

Kumar,

Mallick

et al. 2023

ACS Appl. Polym. Mater.

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Because of the high proton conductivity and thermal stability, Nafion is a reliable material for proton-exchange membranes (PEMs) and is inevitably used in fuel-cell studies. As an alternative to Nafion, covalent–organic frameworks containing sulfonate or phosphate terminals can be used. However, to achieve considerable proton conductivity, high temperature (ca. 120 °C) is often required. Herein, a microporous triazole-functionalized organic polymer (TPOP) is prepared via the condensation of 3,5-diaminotriazole and formaldehyde. The repeating unit of TPOP was identified by 13C cross-polarization magic angle spinning (CPMAS) and core-level C 1s and N 1s X-ray photoelectron spectroscopy (XPS) studies. TPOP possesses a specific surface area (SABET) of 380 m2 g–1 with a pore volume of 1.02 cm3 g–1, while multimodal pore distribution (0.4, 0.9, and 2.2 nm) implicates its microporous nature. The presence of triazole units in the pores of TPOP results in facile proton conduction with a solution-state conductivity of 0.025 S cm–1. An experimentally determined activation energy of 0.285 eV highlights the fact that proton shuttling follows the Grotthuss pathway. The crucial role of the triazole unit in proton conduction is established by considering a reference polymer made of 1,3-diaminobenzene and formaldehyde (MPOP), which contains a phenyl ring in the repeating unit instead of a triazole ring. MPOP shows poor conduction and requires a high activation barrier. This emphasizes the role of triazole nitrogen as a strong Lewis base center to facilitate the proton relay. The facile proton conduction of TPOP provides further scope to study the electrocatalytic hydrogen evolution reaction (HER) using TPOP as a metal-free cathode material. The HER activity of TPOP is not only better than MPOP but also fair compared to some reported porous organic polymers. Considering the demand for low-cost materials for PEM and suitable replacement of noble metals for HER, this triazole-based polymer, TPOP, can serve as a bifunctional metal-free energy material.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Chaudhary,

Kumar,

Mallick

et al. 2023

ACS Appl. Polym. Mater.

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“…In addition, at the fixed current density of 10 mA cm –2 , the overpotentials of Pt/C, p -Ni x Co 9– x S 8 , Ni x Co 9– x S 8 , Co 9 S 8 , and Ni 9 S 8 are 18, 137, 161, 166, and 184 mV, respectively. As a benefit from the abundant active sites, p -Ni x Co 9– x S 8 nanosheets perform better HER behaviors than other Co–Ni sulfide materials. ,− …”

Section: Resultsmentioning

confidence: 99%

Efficient Hydrogen Evolution Catalysts Based on Hierarchical Flowerlike Ni_xCo_9–xS₈ Nanosheets

et al. 2023

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In terms of the need for a low-carbon economy and alleviating the need for energy security, hydrogen (H 2 ) plays a key role in promoting a sustainable economy because it is clean and efficient. The bottleneck of the hydrogen evolution reaction (HER) can be overcome by developing high-efficiency electrocatalysts. Using a simple solvothermal method, p-Ni x Co 9−x S 8 with polyvinylpyrrolidone (PVP) compounds are successfully prepared with synergistic effects between bimetallic sulfides. The resulting p-Ni x Co 9−x S 8 catalyst shows a hierarchical flowerlike nanosheet shape based on physical representations. An ultrathin and porous nanosheet surface facilitates rapid electrolyte injection and provides abundant active sites for H + adsorption, thus giving p-Ni x Co 9−x S 8 nanosheets outstanding HER performance. Furthermore, the synergistic effect of a bimetallic electrocatalyst is helpful to improve HER activity. In comparison to Ni x Co 9−x S 8 nanosheets without PVP, individual Co 9 S 8 particles, and individual Ni 9 S 8 nanosheets, p-Ni x Co 9−x S 8 nanosheets have a lower overpotential (137 mV to 10 mA cm −2 ), Tafel slope (109 mV dec −1 ), and 95.7% retention of current after 1000 cycles in the HER process.

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“…Presumably, the presence of unpaired d-orbital electrons facilitates the chemisorption of protons and/or any other intermediates and favors the catalytic reaction for HER. − The better activity can be correlated to its faster electro-kinetics as the calculated Tafel slope was 94 mV dec –1 , which was again a minimum compared to the other copper loading (Figure b). The electrochemical surface area (ECSA) directly correlates the number of catalytically active sites and can be measured from the double-layer capacitance ( C dl ) value. − The experimentally determined C dl value is 0.51 mF cm –2 , and it is almost double compared to that of PAP. It is intriguingly indicated that the surface-active species were predominately enhanced on copper incorporation and the copper ion is presumably the active site for HER (Figure c, Figure S16), which comes from the lowering of C dl .…”

Section: Resultsmentioning

confidence: 99%

Elucidating the Role of Atomically Dilute Copper Centers Impregnating a Phosphamide Polymer for the Preferential Hydrogen Evolution Reaction over CO₂ Reduction

Chaudhary,

Adak,

Dhananjay

et al. 2023

Inorg. Chem.

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Organic polymers have attracted considerable interest in designing a multifunctional electrocatalyst. However, the inferior electro-conductivity of such metal-free polymers is often regarded as a shortcoming. Herein, a nitrogen-and phosphorus-rich polymer with phosphamide functionality (PAP) in the repeating unit has been synthesized from diaminopyridine (DAP) and phenylphosphonic dichloride (PPDC) precursors. The presence of phosphamide oxygen and pyridine nitrogen in the repeating unit of PAP leads to the coordination of the Cu II ion and the incorporation of 3.29 wt % in the polymer matrix (Cu 30 @PAP) when copper salt is used to impregnate the polymer. Combined with a spectroscopic, microscopic, and DFT study, the coordination and geometry of copper in the PAP matrix has been established to be a distorted square planar Cu II in a N 2 O 2 ligand environment where phosphamide oxygen and pyridine nitrogen of the PAP coordinate to the metal center. The copper incorporation in the PAP modulates its electrocatalytic activity. On the glassy carbon electrode, PAP shows inferior activity toward the hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 while 3 wt % copper incorporation (Cu 30 @PAP) significantly improves the HER performance with an overpotential of 114 mV at 10 mA cm −2 . The notable electrochemical activity with Cu 30 @PAP occurs due to the impregnation of Cu(II) in PAP, improved electro-kinetics, and better charge transfer resistance (R ct ). When changing the electrolyte from H 2 SO 4 to CO 2 -saturated bicarbonate solution at nearly neutral pH, PAP shows HER as the dominant pathway along with the partial reduction of CO 2 to formate. Moreover, the use of Cu 30 @PAP as an electrolcatalyst could not alter the predominant HER path, and only 20% Faradaic efficiency for the CO 2 reduced products has been achieved. Post-chronoamperometric characterization of the recovered catalyst suggests an unaltered valence state of the copper ion and the intact chemical structure of PAP. DFT studies unraveled that the copper sites of Cu 30 @PAP promote water adsorption while phosphamide−NH of the PAP can weakly hold the CO 2 adduct via a hydrogen bonding interaction. A detailed calculation has pointed out that the tetra-coordinated copper centers present in the PAP frame are the reactive sites and that the formation of the [Cu I −H] intermediate is the ratelimiting step for both HER and its competitive side reaction, i.e., CO 2 reduction to formate or CO formation. The high proton concentration in the electrolyte of pH < 7 leads to HER as the predominant pathway. This combined experimental and theoretical study has highlighted the crucial role of copper sites in electrocatalysis, emphasizing the plausible reason for electrocatalytic selectivity.

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Rational design of free-standing 3D Cu-doped NiS@Ni2P/NF nanosheet arrays for hydrogen evolution reaction

Cited by 10 publications

References 57 publications

Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Efficient Hydrogen Evolution Catalysts Based on Hierarchical Flowerlike Ni_xCo_9–xS₈ Nanosheets

Elucidating the Role of Atomically Dilute Copper Centers Impregnating a Phosphamide Polymer for the Preferential Hydrogen Evolution Reaction over CO₂ Reduction

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Rational design of free-standing 3D Cu-doped NiS@Ni2P/NF nanosheet arrays for hydrogen evolution reaction

Cited by 10 publications

References 57 publications

Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Facile Proton Relay in the Triazole Framework to Promote the Electrocatalytic Hydrogen Evolution Reaction

Efficient Hydrogen Evolution Catalysts Based on Hierarchical Flowerlike NixCo9–xS8 Nanosheets

Elucidating the Role of Atomically Dilute Copper Centers Impregnating a Phosphamide Polymer for the Preferential Hydrogen Evolution Reaction over CO2 Reduction

Contact Info

Product

Resources

About

Efficient Hydrogen Evolution Catalysts Based on Hierarchical Flowerlike Ni_xCo_9–xS₈ Nanosheets

Elucidating the Role of Atomically Dilute Copper Centers Impregnating a Phosphamide Polymer for the Preferential Hydrogen Evolution Reaction over CO₂ Reduction