RESUMEN
Renewable energy electrolysis of water to produce hydrogen is an effective measure to break the energy dilemma. However, achieving activity and stability at a high current density is still a key problem in water electrolyzers. Transition metal phosphides (TMPs), with high activity and relative inexpensiveness, have become excellent candidates for the production of highly pure green hydrogen for industrial applications. In this mini-review, multilevel regulation strategies including nanoscale control, surface composition and interface structure design of high-performance TMPs for hydrogen evolution are systematically summarized. On this basis, in order to achieve large-scale hydrogen production in industry, the hydrogen evolution performance and stability of TMPs at a high current density are also discussed. Peculiarly, the practical application and requirements in proton exchange membrane (PEM) or anion exchange membrane (AEM) electrolyzers can guide the advanced design of regulatory strategies of TMPs for green hydrogen production from renewable energy. Finally, the challenges and prospects in the future development trend of TMPs for efficient and industrial water electrolysis are given.
RESUMEN
The hydrogen evolution reaction activity of carbon-supported Pt catalyst is highly dependent on Pt-C interfaces. Herein, we focus on the relationships between Pt activity and N/O-functionalized hollow carbon sphere (HCS) substrate in acidic media. The electrochemical dissolution of Pt counter electrode is performed to prepare Pt nanoparticles in low loading. The N groups are beneficial for homogeneously sized Pt nanoparticles, whereas the O groups lead to aggregated nanoparticles. Moreover, the proper electronegativity of the N groups may enable capturing of protons to create proton-rich Pt-C interfaces and transfer them onto the Pt sites. The O groups may also capture protons by hydrogen bonding, but the subsequent release of protons is more difficult due to a stronger electronegativity and result in an inferior Pt activity. Consequently, the N-doped HCS with a low Pt loading (1.7 µg cm-2 and 0.05 wt %) possesses a higher intrinsic activity compared with Pt on O-doped HCS. Moreover, it outperforms the commercial 20% Pt/C with a stable operation for 12 h. This work may provide suggestions for constructing the advantageous Pt-C interfaces by proper functional groups for high catalytic efficiencies.
RESUMEN
The traditional synthesis for bimetallic-based electrocatalysts is challengeable for fine composition and elemental distribution because of the uncontrollable growth speed of nanostructures utilizing metal salt precursors. Herein, a unique electrochemical corrosion engineering strategy is developed via electrochemically transforming metal solid substrates (iron foil and nickel foam) into a highly active Ni-Fe oxide film for oxygen evolution, rather than directly utilizing metal ion precursors. This synthesis involves electrochemical corrosion of a Fe foil in an aqueous electrolyte along with electrochemical passivation of Ni foam (NF). The released trace Fe ions gradually incorporate into passivated NF surfaces to construct Ni-Fe oxide film and crucially improve composition distribution in the catalyst film. As a result, the resulted film with an ultralow mass loading (0.22 mg cm-2) delivers large current densities of 500 mA cm-2 at overpotential of only 270 mV in 6.0 M KOH at 60 °C, outperforming many reported NiFe catalysts requiring much higher mass loadings. More interestingly, the as-prepared catalyst almost reaches the standard (500 mA cm-2 within the overpotential of 300 mV) in commercial water electrolysis with long-term stability for at least 10 h. This work may provide a unique synthesis strategy for nonprecious transition-metal catalysts for desirable water splitting and can be expanded to many other electrocatalysis systems.
RESUMEN
The surface composite and morphology of binary metal sulfides are the key for efficient overall water splitting. However, tuning the morphology and surface composition of binary metal sulfides in a facile way is still a challenge. Herein, binary Fe-Ni sulfides supported on nickel foam (FeNi-S/NF) with different morphology and composition ratio of Fe/Ni have been synthesized through a facile one-step electrodeposition assisted by liquidcrystaltemplate (LCT). The binary FeNi-S has improved activity and conductivity compared to single metal sulfides. LCT-assisted porous FeNi-S film composed of uniform nanospheres is obviously different from planar film electrodeposited in water solution. LCT-assisted FeNi-S nanospheres are covered by many interwoven nanosheets, implying more exposed active sites for water splitting. Furthermore, the different Fe/Ni ratios of FeNi-S/NF samples have been systematically studied to explore the influence of Fe-incorporation on intrinsic activity of FeNi-S/NF. And the sample with Fe/Ni ratio (3/1) demonstrates the best activity and excellent stability for overall water electrolysis. Therefore, our work provides a facile and controllable access to binary metal sulfides with excellent performances for overall water splitting.
RESUMEN
MoO42-@aniline-pyrrole (MoO42-@polymer) spheres as precursors have been used to synthesize unique core-shell nanostructure consisting of molybdenum carbide and molybdenum phosphide composites encapsulated into uniformly dual N, P-doped carbon shells (Mo2C/MoP@NPC) through a facile two-step strategy. Firstly, porous core-shell N-doped Mo2C@C (Mo2C@NC) nanospheres have been synthesized with ultrafine Mo2C nanoparticles as core and ultrathin NC as shell by a annealing route. Secondly, Mo2C/MoP@NPC has been obtained maintaining intact spherical-like morphology through a phosphidation reaction in high temperature. The synergistic effect of Mo2C and MoP may reduce the strong MoH bonding energy of pure Mo2C and provide a fast hydrogen release process. In addition, the dual N, P-doped carbon matrix as shell can not only improve the electroconductivity of catalysts but also prevent the corrosion of Mo2C/MoP nanoparticles during the electrocatalytic process. When used as HER cathode in acids, the resulting Mo2C/MoP@NPC shows excellent catalytic activity and durability, which only needs an overpotential of 160â¯mV to drive 10â¯mAâ¯cm-2. Moreover, it also exhibits better HER performance in basic and neutral media with the need for overpotentials of only 169 and 228â¯mV to achieve 10â¯mAâ¯cm-2, respectively. This inorganic-organic combination of Mo-based catalysts may open up a new way for water-splitting to produce large-scale hydrogen.
RESUMEN
OBJECTIVE: To investigate the effect of treatment of osteoporotic proximal humeral fractures in elderly patients with a proximal humeral internal locking system (PHILOS) and minimally invasive injectable graft (MIIG). METHODS: Patients who conformed to the inclusion criteria were randomly divided into two groups: group A (21 cases) were treated with PHILOS alone and group B (29 cases) were treated with PHILOS augmentation plus minimally invasive injectable graft (MIIG) X3 Hivisc. Postoperative follow-up was performed regularly to check for complications, reduction loss and fracture healing by imaging. Shoulder joint function was scored and clinical results evaluated according to the Neer scoring system. RESULTS: All patients were followed-up and achieved fracture healing. The complication rate in group A (six cases) was greater than in group B (one case), the differences being statistically significant. The reduction loss in group A (2.9 ± 0.4 mm) was greater than in group B (1.5 ± 0.3 mm), this difference also being statistically significant. According to the Neer system, the excellent and good rate was 76.2% in group A and 82.8% in group B. CONCLUSION: PHILOS using MIPPO and augmented with MIIG X3 Hivisc produces satisfactory clinical results in aged patients with osteoporotic proximal humeral fractures and the method has advantages such as relatively minor trauma, stable fixation, fewer complications, and better joint function.
