Boosting Electrocatalytic Activity of Binary Ag-Fe-doped Co 2 P Nanospheres as Bifunctional Electrocatalysts for Overall Water Splitting

Transition Metal Phosphide Nanoarchitectonics for Versatile Organic Catalysis

Transition metal phosphides (TMP) posses unique physiochemical, geometrical, and electronic properties, which can be exploited for different catalytic applications, such as photocatalysis, electrocatalysis, organic catalysis, etc. Among others, the use of TMP for organic catalysis is less explored and still facing many complex challenges, which necessitate the development of sustainable catalytic reaction protocols demonstrating high selectivity and yield of the desired molecules of high significance. In this regard, the controlled synthesis of TMP-based catalysts and thorough investigations of underlying reaction mechanisms can provide deeper insights toward practical achievement of desired applications. This review aims at providing a comprehensive analysis on the recent advancements in the synthetic strategies for the tailored and tunable engineering of structural, geometrical, and electronic properties of TMP. In addition, their unprecedented catalytic potential toward different organic transformation reactions is succinctly summarized and critically analyzed. Finally, a rational perspective on future opportunities and challenges in the emerging field of organic catalysis is provided. On the account of the recent achievements accomplished in organic synthesis using TMP, it is highly anticipated that the use of TMP combined with advanced innovative technologies and methodologies can pave the way toward large scale realization of organic catalysis.

Heterogeneous Fe-Doped NiCoP-MoO3 Efficient Electrocatalysts for Overall Water Splitting

Transition metal phosphides with excellent performance are one of the effective alternatives to noble metal catalysts in overall water splitting. In this paper, the Fe-NiCoP-MoO3 composite was prepared by a facile synthesis as the bifunctional electrocatalyst. Fe-NiCoP-MoO3 achieves an operating current density of 10 mA/cm2 at a low overpotential of 65 mV for hydrogen evolution reaction and drives an operating current density of 50 mA/cm2 at only 293 mV for oxygen evolution reaction. Significantly, Fe-NiCoP-MoO3 was employed as the anode and cathode for overall water splitting, which only requires a cell voltage of 1.586 V to reach 10 mA/cm2 as well as shows excellent stability. The electrocatalytic activity of Fe-NiCoP-MoO3 exceeds most of the recently reported typical bifunctional electrocatalysts. This may be due to the coupling effect between the polymetallic phosphides. In addition, heterogeneous catalysts generally expose more active sites than homogeneous catalysts. In addition, replacing MoO3 with WO3 and VO3 can also improve the performance of Fe-NiCoP. This work provides an idea for the modification of phosphides.

Controllable Heteroatom Doping Effects of CrxCo2-xP Nanoparticles: a Robust Electrocatalyst for Overall Water Splitting in Alkaline Solutions

The effect of doping Cr on the electrocatalytic activity of Co₂P supported on carbon black (Cr_xCo_2-xP/CB) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution was investigated. A beneficial improvement in the performance of Co₂P toward HER and OER was discovered. For the HER at -200 mV overpotential, the turnover frequency (TOF) increases almost 6-fold from 0.26 to 1.52 electron site_Co^-1 s^-1 when Co₂P/CB has a small amount of Cr added to form Cr_0.2Co_1.8P/CB. Similarly, we estimate an increase from 0.205 to 0.585 electron site_Co^-1 s^-1 for the OER at 1.6 V for the same change in composition. With 10 atom % Cr doping, the Cr_0.2Co_1.8P/CB catalyst needed 226 mV overpotential to produce a cathodic current density of -100 A g_Co^-1 and 380 mV overpotential to produce an anodic current density of 100 A g_Co^-1. Based on both experimental results and theoretical calculations, the activity improvement results from optimization of the electronic properties of Co₂P after Cr doping.

Plasma-assisted nitrogen doping in Ni-Co-P hollow nanocubes for efficient hydrogen evolution electrocatalysis

To surmount the issues of a limited specific surface area and slow electrolyte diffusion in composite electrocatalysts, three-dimensional (3D) porous hollow nanocubes are fabricated, in which bimetal Ni-Co phosphide composites are covered with nanoparticles. The abundant hollow space provides more active sites for the catalyst, and simultaneously ensures efficient mass transfer and electron transport during the hydrogen evolution reaction (HER). A plasma-assisted approach is employed for smart N-doping in the Ni-Co phosphide hollow nanocubes (N-Ni-Co-P HNCs). The N-Ni-Co-P HNC catalyst exhibits a remarkable HER performance in 1 M KOH, evidenced by the low overpotentials of 47.9 mV and 150.5 mV at the current density of 10 mA cm-2 and 50 mA cm-2, respectively, as well as the excellent long-time stability. Essentially, the N doping tailors the electronic states and optimizes the free energy of hydrogen adsorption (ΔGH*) greatly, and the 3D porous hollow structure with porous nanoparticles stacked enlarges the specific active area substantially. Their synergistic effects result in the remarkably enhanced catalytic activity for the HER.

Coralline-like CoP3@Cu as an efficient electrocatalyst for the hydrogen evolution reaction in acidic and alkaline solutions

CoP₃@Cu/Cu exhibited excellent catalytic activity and stability in acidic and alkaline media.

Enhanced oxygen evolution catalysis by aluminium-doped cobalt phosphide through in situ surface area increase

Al-doping of cobalt phosphide oxygen evolution catalysts results in enhanced performance which, based on in situ and operando analysis, is shown to result from a surface area increase associated with modified oxidation behaviour.

One-Step Route Synthesized Co2 P/Ru/N-Doped Carbon Nanotube Hybrids as Bifunctional Electrocatalysts for High-Performance Li-O2 Batteries

The large-scale commercial application of lithium-oxygen batteries (LOBs) is overwhelmed by the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) associated with insoluble and insulated Li₂ O₂ . Herein, an elaborate design on a highly catalytic LOBs cathode constructed by N-doped carbon nanotubes (CNT) with in situ encapsulated Co₂ P and Ru nanoparticles is reported. The homogeneously dispersed Co₂ P and Ru catalysts can effectively modulate the formation and decomposition behavior of Li₂ O₂ during discharge/charge processes, ameliorating the electronically insulating property of Li₂ O₂ and constructing a homogenous low-impedance Li₂ O₂ /catalyst interface. Compared with Co/CNT and Ru/CNT electrodes, the Co₂ P/Ru/CNT electrode delivers much higher oxygen reduction triggering onset potential and higher ORR and OER peak current and integral areas, showing greatly improved ORR/OER kinetics due to the synergistic effects of Co₂ P and Ru. Li-O₂ cells based on the Ru/Co₂ P/CNT electrode demonstrate improved ORR/OER overpotential of 0.75 V, excellent rate capability of 12 800 mAh g^-1 at 1 A g^-1 , and superior cycle stability for more than 185 cycles under a restricted capacity of 1000 mAh g^-1 at 100 mA g^-1 . This work paves an exciting avenue for the design and construction of bifunctional catalytic cathodes by coupling metal phosphides with other active components in LOBs.

Ag nanoparticle-decorated, ordered mesoporous silica as an efficient electrocatalyst for alkaline water oxidation reaction

Ag NPs were decorated on the surface of a functionalized SBA-15 material and the resulting AgNPs@SBA-NH₂ material showed excellent OER activity for electrochemical water oxidation under alkaline pH.

Mn doped CoP nanoparticle clusters: an efficient electrocatalyst for hydrogen evolution reaction

Electrodeposited CoMn LDH was in situ converted to Mn-CoP electro-catalysts which show excellent HER activity in both acidic and alkaline solutions.