Synergetic effect of Au nanoparticles and transition metal phosphides for enhanced hydrogen evolution from ammonia-borane

Strain Engineering for Electrocatalytic Overall Water Splitting

Strain engineering is a novel method that can achieve superior performance for different applications. The lattice strain can affect the performance of electrochemical catalysts by changing the binding energy between the surface-active sites and intermediates and can be affected by the thickness, surface defects and composition of the materials. In this review, we summarized the basic principle, characterization method, introduction strategy and application direction of lattice strain. The reactions on hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are focused. Finally, the present challenges are summarized, and suggestions for the future development of lattice strain in electrocatalytic overall water splitting are put forward.

Recent Advancements in Ascribing Several Platinum Free Electrocatalysts Pertinent to Hydrogen Evolution from Water Reduction

The advancement of a sustainable and scalable catalyst for hydrogen production is crucial for the future of the hydrogen economy. Electrochemical water splitting stands out as a promising pathway for sustainable hydrogen production. However, the development of Pt-free electrocatalysts that match the energy efficiency of Pt while remaining economical poses a significant challenge. This review addresses this challenge by highlighting latest breakthroughs in Pt-free catalysts for the hydrogen evolution reaction (HER). Specifically, we delve into the catalytic performance of various transition metal phosphides, metal carbides, metal sulphides, and metal nitrides toward HER. Our discussion emphasizes strategies for enhancing catalytic performance and explores the relationship between structural composition and the performance of different electrocatalysts. Through this comprehensive review, we aim to provide insights into the ongoing efforts to overcome barriers to scalable hydrogen production and pave the way for a sustainable hydrogen economy.

P-bridged Fe-X-Co coupled sites in hollow carbon spheres for efficient hydrogen generation

Non-precious metals have shown attractive catalytic prospects in hydrogen production from ammonia borane hydrolysis. However, the sluggish reaction kinetics in the hydrolysis process remains a challenge. Herein, P-bridged Fe-X-Co coupled sites in hollow carbon spheres (Fe-CoP@C) has been synthesized through in situ template solvothermal and subsequent surface-phosphorization. Benefiting from the optimized electronic structure induced by Fe doping to enhance the specific activity of Co sites, bimetallic synergy and hollow structure, the as-prepared Fe-CoP@C exhibits superior performances with a turnover frequency (TOF) of 183.5 min-1, and stability of over 5 cycles for ammonia borane hydrolysis, comparable to noble metal catalysts. Theoretical calculations reveal that the P-bridged Fe-X-Co coupled sites on the Fe-CoP@C catalyst surfaces is beneficial to adsorb reactant molecules and reduce their reaction barrier. This strategy of constructing hollow P-bridged bimetallic coupled sites may open new avenues for non-precious metal catalysis.

Selective and efficient H2 evolution upon NH3BH3 hydrolysis at subzero temperatures

In the winter months, the temperature in most of the Earth stays below 0°C; the average temperature in winter at the South Pole is about -60°C. Therefore, it is urgent to develop efficient catalytic systems for selective and efficient H2 evolution upon NH3BH3 hydrolysis at subzero temperatures. For solving the freezing issue of water at below 0°C, herein, we have employed a facile and surfactant-free approach to synthesize M-Pt/C nanocomposites (M = Pd, Rh, Ru, Ni, Cu, or Fe), by the alloying of commercial Pt/C with Pd, Rh, Ru, Cu, Ni, or Fe for selective and efficient H2 evolution upon NH3BH3 hydrolysis in saline solution at below 0°C, even at -15°C. In addition, NH3BH3 hydrolysis over Pd-Pt/C in the saturated NaCl solution is utilized not only for safe hydrogen production but also for its in situ hydrogenation reduction in organic chemistry, which could avoid using dangerous hydrogen cylinders.

Modulating Electronic Metal-Support Interactions to Boost Visible-Light-Driven Hydrolysis of Ammonia Borane: Nickel-Platinum Nanoparticles Supported on Phosphorus-Doped Titania

Ammonia borane (AB) is a promising material for chemical H2 storage owing to its high H2 density (up to 19.6 wt %). However, the development of an efficient catalyst for driving H2 evolution through AB hydrolysis remains challenging. Therefore, a visible-light-driven strategy for generating H2 through AB hydrolysis was implemented in this study using Ni-Pt nanoparticles supported on phosphorus-doped TiO2 (Ni-Pt/P-TiO2 ) as photocatalysts. Through surface engineering, P-TiO2 was prepared by phytic-acid-assisted phosphorization and then employed as an ideal support for immobilizing Ni-Pt nanoparticles via a facile co-reduction strategy. Under visible-light irradiation at 283 K, Ni40 Pt60 /P-TiO2 exhibited improved recyclability and a high turnover frequency of 967.8 molH 2 ${{_{{\rm H}{_{2}}}}}$  molPt -1  min-1 . Characterization experiments and density functional theory calculations indicated that the enhanced performance of Ni40 Pt60 /P-TiO2 originated from a combination of the Ni-Pt alloying effect, the Mott-Schottky junction at the metal-semiconductor interface, and strong metal-support interactions. These findings not only underscore the benefits of utilizing multipronged effects to construct highly active AB-hydrolyzing catalysts, but also pave a path toward designing high-performance catalysts by surface engineering to modulate the electronic metal-support interactions for other visible-light-induced reactions.

Facile construction of robust Ru-Co3O4 Mott-Schottky catalyst enabling efficient dehydrogenation of ammonia borane for hydrogen generation

Developing efficient catalysts for the dehydrogenation of ammonia borane (AB) is important for the safe storage and controlled release of hydrogen, but it is a challenging task. In this study, we designed a robust Ru-Co₃O₄ catalyst using the Mott-Schottky effect to induce favorable charge rearrangement. The self-created electron-rich Co₃O₄ and electron-deficient Ru sites at heterointerfaces are indispensable for the activation of the B-H bond in NH₃BH₃ and the OH bond in H₂O, respectively. The synergistic electronic interaction between the electron-rich Co₃O₄ and electron-deficient Ru sites at the heterointerfaces resulted in an optimal Ru-Co₃O₄ heterostructure that exhibited outstanding catalytic activity for the hydrolysis of AB in the presence of NaOH. The heterostructure had an extremely high hydrogen generation rate (HGR) of 12238 mL min^-1 g_cat^-1 and an expected high turnover frequency (TOF) of 755 mol_H2 mol_Ru^-1 min^-1 at 298 K. The activation energy needed for the hydrolysis was low (36.65 kJ mol^-1). This study opens up a new avenue for the rational design of high-performance catalysts for AB dehydrogenation based on the Mott-Schottky effect.