Metal phosphides (MPs) with unique and desirable physicochemical properties provide promising potential in practical applications, such as the catalysis, gas/humidity sensor, environmental remediation, and energy storage fields, especially for transition metal phosphides (TMPs) and MPs consisting of group IIIA and IVA metal elements. Most studies, however, on the synthesis of MP nanomaterials still face intractable challenges, encompassing the need for a more thorough understanding of the growth mechanism, strategies for large-scale synthesis of targeted high-quality MPs, and practical achievement of functional applications. This review aims at providing a comprehensive update on the controllable synthetic strategies for MPs from various metal sources. Additionally, different passivation strategies for engineering the structural and electronic properties of MP nanostructures are scrutinized. Then, we showcase the implementable applications of MP-based materials in emerging sustainable catalytic fields including electrocatalysis, photocatalysis, mild thermocatalysis, and related hybrid systems. Finally, we offer a rational perspective on future opportunities and remaining challenges for the development of MPs in the materials science and sustainable catalysis fields.

Nanostructured metal phosphides: from controllable synthesis to sustainable catalysis.

Supercapacitors, also known as electrochemical capacitors, have attracted more and more attention in recent decades due to their advantages of higher power density and long cycle life. For the real application of supercapacitors, there is no doubt that cyclic stability is the most important aspect. As the core component, electrode materials determine the cyclic stability of supercapacitors, although the other components like electrolyte and separator are also important. In this review, we sum up the cyclic stability of supercapacitors according to type of electrode material and its energy storage mechanism, discuss the strategies to boost the stability of those electrode materials, and indicate several key significant considerations in measurement of cyclic stability. The purpose is to obtain safe, long-lasting, and high-performance supercapacitor devices.

Cyclic stability of supercapacitors: materials, energy storage mechanism, test methods, and device

Enhanced the energy density of supercapacitors via rose-like nanoporous ZnGa2S4 hollow spheres cathode and yolk-shell FeP hollow spheres anode

Nonprecious transition metal‐organic frameworks (MOFs) are one of the most promising precursors for developing electrocatalysts with high porosity and structural rigidity. This study reports the synthesis of high efficiency electrocatalysts based on S‐doped NiFeP. MOF‐derived S‐doped NiFeP structure is synthesized by a one‐step phosphorization process with using S‐doped MOFs as the precursor, which is more convenient and environment friendly, and also helps retain the samples’ framework. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the NiFeP catalysts can be improved after partially replacing P by S due to the tunable electronic structure. The optimized CCS‐NiFeP‐10 reaches a current density of 10 mA cm–2 for OER with an overpotential of 201 mV and outperforms most NiFe‐based catalysts. The S doping plays an important role in tuning the ΔG values for intermediates formation in Ni atoms to a suitable value and exhibits a pronouncedly improved the OER performance. CCS‐NiFeP‐20 sample presents excellent HER performance due to the d‐band center downshifting from the Fermi level. When the voltage of the electrolytic cell is 1.50 V, a current density of 10 mA cm–2 can be obtained. This strategy paves the way for designing highly active none‐noble metal catalysts.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adfm.202200733

Electron Redistributed S‐Doped Nickel Iron Phosphides Derived from One‐Step Phosphatization of MOFs for Significantly Boosting Electrochemical Water Splitting

Tailoring nanostructured transition metal phosphides for high-performance hybrid supercapacitors

Designing excellent electrode materials by establishing superb architectures provides a feasible way to boost the electrochemical properties of supercapacitors (SCs). Herein, a self-supported bimetallic Ni–Fe phosphide (Ni–Fe–P) electrode with a newfangled and multidimensional construction was synthesized by a two-step process. This electrode consists of connective nanosheets which combined numerous interlinked nanoparticles with well-distributed mesopores. By investigating the effects of phosphating temperatures, an optimal phosphide electrode with well-distributed pores throughout the interlaced nanosheets has been obtained. Due to this sophisticated porous structure and the mechanical stability enhanced by the direct growth on binderless Ni foam, the Ni–Fe–P electrode exhibits outstanding electrochemical performance. Density functional theory (DFT) calculations are also performed to demonstrate the increased electrical conductivity and reactivity after the introduction of Fe atoms and phosphorization. Impressively, the fabricated Ni–Fe–P//reduced graphene oxide solid-state SC device delivers an outstanding energy density of 50.2 W h kg−1 at a power density of 800 W kg−1, and remarkable cycle performance (91.5% retention rate after 10 000 cycles). This comprehensive work not only displays a new perspective of the phosphating mechanism at different temperatures but also suggests a versatile approach for engineering promising electrode materials for advanced SCs.

Self-supported multidimensional Ni–Fe phosphide networks with holey nanosheets for high-performance all-solid-state supercapacitors

Flexible supercapacitors (SCs) have become a popular research topic due to their extra-long service life, foldability, and wearability. Nevertheless, their low energy density restricts their applications. Here, we synthesized phosphorus-doped bimetallic sulfides embedded in hetero-atom-doped (N, S, and P) carbon shells (P-ZCS/HC) using a simple approach to create high-performance flexible electrodes. The three-dimensional architecture made by interlaced nanosheets was preserved, and raised nanoparticles appeared on the rough surface during the annealing operation, increasing the specific surface area and potential exposure to the electrolyte. It is noteworthy that the optimal P-ZCS/HC electrode possessed a remarkable capacity of 1080 C g−1 at 1 A g−1 along with superb cycling stability. These extraordinary properties were primarily caused by plentiful redox reactions, enhanced conductivity, and synergic effects of the P-doped metal sulfides and heteroatom-doped carbon shells. Density functional theory simulations confirmed the good function of the P-doped electrodes and their ability to boost conductivity, improve reactive dynamics, and promote OH− adsorption. Notably, the assembled all-solid-state hybrid SC exhibited a maximum energy density of 62.9 W h kg−1 and a power density of 16 kW kg−1, while being able to maintain 92.0% of its initial capacity after 10,000 cycles. This systematic report provides new insight into the design and synthesis of electrodes with complex components and outstanding structures for the flexible energy field.

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Phosphorous-doped bimetallic sulfides embedded in heteroatom-doped carbon nanoarrays for flexible all-solid-state supercapacitors

To steadily produce high-quality vermicular graphite cast iron (VGI), it is essential to have a deep understanding of the growth mechanism of vermicular graphite. The morphology and microstructure of graphite in VGI were studied using various techniques, including both experimental and theoretical methods. An abnormal graphite structure with an anomalous layer distance of 6.60 A was observed by transmission electron microscopy (TEM) imaging, which is approximately two times larger than the normal structure (3.40 A). The theoretical simulations of possible trace elements added (approximately 34 different elements) to the graphite basal planes were studied and analyzed individually to understand the observed phenomenon and their effects on graphite growth. The theoretical calculations (6.56 A) show good agreement with the experimental results (6.60 A), which proves that the lattice anomaly is caused by Mg. The abnormal graphite was believed to be the remains of the transition state during the growth of graphite. Based on the investigation, a mechanism is proposed to describe the influence of Mg during the growth process of vermicular graphite.

Minghao Hua

Papers

Self-supported multidimensional Ni–Fe phosphide networks with holey nanosheets for high-performance all-solid-state supercapacitors

Phosphorous-doped bimetallic sulfides embedded in heteroatom-doped carbon nanoarrays for flexible all-solid-state supercapacitors

Growth mechanisms of vermicular graphite in cast iron