《International Journal of Hydrogen Energy》2023,48(71):27557-27567

Heterostructure and phase engineering are effective method to tune the electronic structure of MoS₂, which can activate and boost its intrinsic catalytic activity. Herein, the theoretical calculations reveal that the free energy of H1 adsorption (ΔG_H1) for Mo₂C (−0.65 eV) is lower than MoS₂ (2.05 eV), which is favorable for hydrogen adsorption. Inspired by the theoretical predictions, we develop a facile strategy to prepare nanostructured Mo₂C/MoS₂ dispersed on reduced graphene oxide (rGO) via a hydrothermal preparation and carburization reaction. Since the Mo₂C/MoS₂-rGO nanostructures with great deal of both MoS₂ and Mo₂C edges by heterostructure and phase engineering, which can induce massive active sites for HER on the surface of rGO, the intimate interfacial coupling effect between Mo₂C and MoS₂ can effectively improve the charge transfer rate. The Mo₂C/MoS₂-rGO catalyst exhibits exceptional HER properties, delivering a high turnover frequency (TOF) of 0.209 s⁻¹ at an overpotential of 200 mV in 0.1 M KOH. This work may open a new window for designing NPM electrocatalysts with highly efficient HER property based on earth-abundant materials.  相似文献   

    

《International Journal of Hydrogen Energy》2023,48(73):28343-28353

The construction of heterostructures is an efficient approach to improve the photocatalystic performance of semiconductors. In this paper, SnO₂-g-C₃N₄ (SnO₂–CN) nanocomposites were created via thermal polymerization using SnO₂ nanoparticles and layered g-C₃N₄ nanosheets. A mechano-chemical pre-reaction and the second thermal polymerization of bulk g-C₃N₄ play important roles for the formation of SnO₂/g-C₃N₄ heterostructures with improved interface nature. The heterostructures with an optimized SnO₂ weight ratio of 10% was obtained by adjusting parameters for enhanced photocatalytic reactions in visible light region. Hydrogen generation and the degradation of rhodamine B (Rh B) were tested to characterize the photocatalytic performance of the SnO₂–CN nanocomposites. The degradation of a 20 mg/L Rh B solution was finished within 15 min, in which the degradation rate was about twice compared with superior thin g-C₃N₄ nanosheets prepared by a two-step polymerization procedure. The SnO₂–CN nanocomposite with 10% SnO₂ revealed a H₂ generation rate of 2569.5 μmol g⁻¹L⁻¹. The enhanced photocatalytic performance is ascribed to a type II heterostructure formed and improved interface properties between g-C₃N₄ and SnO₂. In addition, the improved conductivity of SnO₂ promoted the photogenerated carrier separation and transfer. The result provided a new idea for the construction of g-C₃N₄ heterostructures with improved interface characterization and the improvement of photocatalytic properties.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(5):2936-2946

A high-efficiency and easy-available approach was developed to obtain a ternary heterojunction composites with advanced hydrogen evolution reaction (HER) performance under visible light by water split. PdAg bimetallic nanoparticles make a close contact interface between g-C₃N₄(CN) and Zn_0.5Cd_0.5S(ZCS). Under visible light irradiation, CN and ZCS are both excited to generate electron-hole pairs, PdAg bimetallic nanoparticles act as a bridge between CN and ZCS. Not only can the photogenerated electrons from CN be captured, but they can also be quickly transferred to the surface of ZCS and participate in the photocatalytic reaction to release H₂, and the recombination of charge carriers between the contact interface of ZCS and CN can be significantly inhibited. In addition, the thin CN layer reduces the photocorrosion of the ZCS and enhances the specific surface area of the composite material. After testing, the composite material with 30 wt% ZCS and 4 wt% PdAg demonstrates hydrogen evolution performance, up to 6250.7 μmol g^?1h^?1, which is 753 times the hydrogen evolution rate of single-component CN and 12.6 times of ZCS/CN. Compared with single-component and two-component photocatalysts, the ternary ZCS/PdAg/CN photocatalyst achieves significantly enhanced photocatalytic activity.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(21):11128-11142

Development of novel type bifunctional electrocatalyst containing Fe, Mo, S and O for overall water splitting is important. Either a bimetallic compound or a heterostructure could be developed utilizing these elements however; the widely utilized hydrothermal reaction would favor the formation of the later one. Herein, a unique triethanolamine-assisted strategy was adopted to facilitate the formation of S-doped FeMoO₄ instead of an iron oxide/molybdenum sulfide heterostructure. Through electrochemical investigation revelaed that the said assistance was crucial in achieving excellent bifunctional electrocatalytic activity. The activity of the optimally doped FeMoO₄ (especially towards oxygen evolution reaction) was superior to most of the recently reported transition-metal-based electrocatalysts. Moreover, it achieved 10 mA cm^?2 for overall water splitting at 1.561 V, which was ～60 mV lower than that required for the RuO₂–Pt/C couple. A very high Faradaic efficiency (95.88%) and operational robustness was associated with the overall water splitting catalyzed by S-doped FeMoO₄.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(98):41553-41563

Photocatalytic or photoelectrocatalytic nitrogen fixation is considered as a very promising way to reduce energy requirements. Here, V_o-BiOBr/TiO₂ nanocomposite photoelectrode was constructed by modifying TiO₂ nanotube arrays with BiOBr nanosheets with oxygen vacancies (V_o) for photoelectrocatalytic nitrogen fixation. The oxygen vacancy promotes the adsorption and activation of N₂ on the catalyst surface. The Lewis basicity of nitrogen is enhanced by transferring the photogenerated electrons on the conduction band of BiOBr to the π anti-bonding orbit of N₂, which is more beneficial for the addition of protons. On the other hand, the heterojunction between TiO₂ and V_o-BiOBr facilitates the separation of photogenerated carriers. The photogenerated holes on the valence band of TiO₂ travelled to the counter electrode to produce oxygen at a negative potential, avoiding the further oxidation of NH₃. V_o-BiOBr/TiO₂ displays a high NH₃ production rate of 25.08 μg h^?1 cm^?2 at ?0.2 V which is 3.3 times higher than that of BiOBr/TiO₂. The synergistic effect between TiO₂ and V_o-BiOBr results in enhanced light absorption and higher photoelectrocatalytic efficiency for the N₂ reduction reaction.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(99):41759-41771

III-V materials have gained great interest in materials science community since a few decades due to their versatile properties. Experimenting with the crystal phase, dimensional confinement, chemical environment and external conditions open-up a window to finely tune the properties of material of interest at atomic scale. The density functional theory-based investigation of III-V semiconductors under heterostructure nanowire configuration is presented with specific focus on the electronic dispersion and band alignment. The combination of GaSb core having triangular(T)/circular(R) cross-sections with GaP and GaAs shells reveal formation of type-II heterostructure with moderate electronic band gap suggesting promising application in photocatalysis and photovoltaics. Motivated by these results, we have investigated the catalytic activity of the heterostructure nanowires towards hydrogen evolution reaction (HER). Interesting results showing reliable HER activity over different surface sites of the nanowires evidently approve their importance as an active HER catalyst. Furthermore, being within nano regime, the present systems suggest cost-effective production of HER catalyst as compared to the conventional novel metal-based catalysts.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(47):20518-20528

The transition metal phosphides (TMPs) with highly active and low-cost are imperative electrocatalysts for hydrogen evolution reaction (HER). In particular, metal-rich interface engineering of iron phosphide could effectively modify the active sites for HER and accelerate the charge transfer, thus achieving the promoted efficiency. Herein, we report metal-rich heterostructure of Ag-doped Fe₂P shell attached to FeS core on Fe foams (FeS/Fe₂P–Ag@IF) for HER, which are synthesized by a simple hydrothermal method with subsequent low-temperature phosphorization. Notably, the phosphorization process simultaneously achieves the partial conversion of FeS to Fe₂P, and complete reduction of Ag₂S to Ag. Furthermore, the metal-rich structure of Fe₂P increases the active sites for hydrogen adsorption, which consequently contributes to hydrogen evolution. Simultaneously, the successful doping of metallic Ag enhanced the electroconductivity and the stability of the electrocatalyst. Benefiting from the ternary synergistic effect at FeS/Fe₂P–Ag@IF and metallic Ag doping, the optimal Ag-doped FeS/Fe₂P electrocatalyst exhibits a low overpotential of 214.9 mV at 100 mA cm^?2, even surviving at this large current density with long-term stability. This promising strategy involving metallic Ag doping may be a suitable option for the development of iron-based metal-rich phosphides heterostructured for HER.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(47):20448-20461

Developing the novel catalysts with an excellent performance of hydrogen generation is essential to facilitate the application of hydrogen evolution reaction (HER). Herein, a heterostructured cobalt phosphide/nickel phosphide/carbon cloth (CoP/Ni₂P/CC) composite was fabricated via an interfacial engineering strategy to achieve the modification of CoP nanoleaf on Ni₂P nanosheet skeleton supported by carbon cloth. By virtue of the unique heterostructure, abundant exposing active sites and the synergistic coupling effect of CoP and Ni₂P nanoparticles, the elaborated CoP/Ni₂P/CC composite exhibits a robust catalytic property. Among fabricated composites, the optimal CoP/Ni₂P/CC-4 catalyst behaves an excellent HER performance at a wide pH range (overpotentials of 67, 71 and 95 mV to afford 10 mA cm^?2 in 0.5 M H₂SO₄, 1 M KOH and 1 M PBS, respectively). The HER current density of this composite shows a negligible degradation after continuous test for 24 h. Charmingly, the HER process of this catalyst was innovatively applied to reduce graphene oxide, and thus exploiting the fabrication route of reduced graphene oxide (rGO). We are sure that this work will provide a firm guideline for the exploitation of pH-universal HER catalysts and the exploration of HER application.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(59):24669-24679

A wide diversity of phosphides of platinum-group metal including Rh, Ru and Ir exhibit intriguing electrocatalytic activity toward hydrogen evolution reaction (HER). The phosphidation degree, namely the P dosage in these phosphides shows pronounced influence on the catalytic performance but is hard to control. In this work we developed a reliable strategy to synthesize Rh₂P-based nanoparticles with controlled phosphidation degree, and investigated the influence of phosphidation degree on HER. It is found that the heterostructured Rh₂P/Rh nanoparticle, i.e., the P-deficient composite with mixed metallic and phosphide phases, outperforms either the metallic Rh or pure Rh₂P nanoparticles. As-synthesized Rh₂P/Rh nanoparticles supported on P/N co-doped graphene (denoted as Rh₂P/Rh-G) display remarkable HER activity with tiny overpotential of 17 and 19 mV at 10 mA cm^?2 current density in alkaline and acid, efficiently surpassing its Rh-based rivals and benchmark Pt/C catalyst. Meanwhile it illustrates a large mass-specific activity (3.23 and 6.26 A mg^?1 @50 mV overpotential in alkaline and acid, respectively) due to its high activity and low metal loading. Density functional theory (DFT) calculation indicates that the Rh₂P/Rh heterostructured interface possesses the optimal close-to-zero value of hydrogen adsorption energy and water dissociation process is accelerated, and thus boosts HER activity.  相似文献   

    

《International Journal of Hydrogen Energy》2022,47(66):28434-28447

A potential non-noble metal oxide catalyst with its low-cost and efficient catalytic ability attract increasing attention. In this paper, a highly efficient bifunctional electrocatalyst Co||MnCo₂O_4.5/NC with heterostructure and oxygen vacancies is prepared utilizing solid reaction in-situ. The optimal catalyst is obtained at 650 °C with the mass ratio (1:8) of MnCo₂O_4.5 and Dicyandiamide (DCD). It shows excellent electrocatalytic activity for oxygen reduction reaction (ORR) with high half-wave potential (0.81 V) and limit current density (6.22 mA cm^?2), which is better than that of the commercial 20% Pt/C(0.81 V, 5.52 mA cm^?2). At the same time, it also exhibits superior electrocatalytic activity for oxygen evolution reaction (OER) with low overpotential (330 mV) and a faster dynamics process. The superior electrocatalytic properties may be resulted from the presence of heterostructure and increasing ratio of oxygen vacancies, which helps to the rapid transfer of electrons and creates more active sites. Moreover, the self-generated N-doped carbon provides high conductivity of the as-prepared Co||MnCo₂O_4.5/NC composite. It can be seen that the application of interface engineering technologies is useful for improving the performance of the catalyst, providing an effective and facile synthesis strategy for non-noble metal catalyst.  相似文献