Production of hydrogen (H2) from H2 storage materials is very attractive as a source of sustainable energy. We report that [email protected] alloys are very efficient nanocatalysts for H2 evolution upon ammonia borane hydrolysis under visible-light illumination with turnover frequency 3.4 times higher than with the monometallic Ni catalyst in the dark. This improvement is attributed to dramatic volcano-type positive synergy optimized in Au0.5Ni0.5 @ZIF-8, for which ZIF-8 is by far the superior support, as well as to the localized surface plasmon resonance induced between 450 and 620 nm. Infrared spectra analysis and tandem reaction confirm the origin of the hydrogen atoms, reveal the reaction mechanism, and suggest how the cleavage of the B–H and O–H bonds proceeds in this reaction. Deuteration experiments with D2O including primary kinetic isotope effects and density functional theory calculation under both dark and visible light conditions show that activation of H2O always is the rate-determining step. 

Fast Au-Ni@ZIF-8-catalyzed ammonia borane hydrolysis boosted by dramatic volcano-type synergy and plasmonic acceleration

Rational construction of inexpensive, highly efficient, and stable catalysts for ammonia borane (AB) methanolysis is in high demand but still remains a great challenge. In this work, we have successfully fabricated uniform Mox-Ni0.8Cu0.2O nanowires using a simple hydrothermal method followed by a post-calcination treatment and flexibly modulated the acidity of their surface by changing the amount of Mo introduced into Ni0.8Cu0.2O. The Mo0.1-Ni0.8Cu0.2O catalyst displayed strong catalytic activity toward AB methanolysis with an ultrahigh turnover frequency of 46.9 molH2 molcat.-1 min-1, which is even higher than some noble metal catalysts. In this work, an equation regarding the relationship between the quantity of moderated acid sites of catalysts and its corresponding activity toward AB methanolysis was first determined. A plausible mechanism for AB methanolysis catalyzed by Mox-Ni0.8Cu0.2O was proposed, and the benefits of the introduction of MoO3 to Ni0.8Cu0.2O for enhancing the catalytic performance were also discussed. These findings can form a basis for the rational construction of inexpensive catalysts with robust performance toward AB methanolysis for hydrogen production.

Modulating the Acidic Properties of Mesoporous Mox-Ni0.8Cu0.2O Nanowires for Enhanced Catalytic Performance toward the Methanolysis of Ammonia Borane for Hydrogen Production.

The Pt1/Co3O4-c catalysts exhibit great catalytic activities in hydrolytic dehydrogenation of ammonia borane (AB) with a specific rate of 6035 molH2 molPt-1 min-1 at room temperature. In-situ DRIFTS spectra and...

Crystal Facet Effects of Platinum Single-Atom Catalyst in Hydrolytic Dehydrogenation of Ammonia Borane

Hydrogen production from borohydride hydrolysis is a green and sustainable route to convert hydrogen energy. In the progress, the regulation of electron enrichment and distribution around the active site is the key to promote hydrogen-adsorption during hydrogen production. Here, we fabricated an out-of-plane CoRu nanoalloy axially coupling Co s NC for high electron attachment in hydrolysis of ammonia borane. The axially coupling of out-of-plane CoRu nanoalloy on Co s NC surface for electron enrichment enhances the hydrogen bonding (H*) energy and cycle life. The hydrogen production efficiency (1068 mol H2 mol Ru −1 min −1 ) and activation energy (18.96 kJ mol −1 ) are the best among reported Co-based alloys. Theoretical calculations show that an electron-integration-boosting effect from axially accurate tailoring of CoRu alloy on Co s NC to reduce the reaction energy barrier for co-activation of AB and H 2 O. This work provides insight into structure-activity identification for efficient hydrogen production. Out-of-plane CoRu nanoalloy axial coupling Co s -N-C with multiatomic active sites is fabricated via solid-surfaces-situ-pyrolysis on Co s NC for efficient NH 3 BH 3 hydrolysis. Axially accurate tailoring of single site (Co s NC) by out-of-plane bimetallic coupling at nano level results in a superior hydrogen generation kinetics of NH 3 BH 3 hydrolysis. The optimized Co 0.5 Ru 0.5 /Co s NC present the highest hydrogen generation kinetics (1.068 ×10 3 mol H2 ·min −1 ·mol Ru −1 , 298 K) and the lowest activation energy (18.96 kJ·mol −1 ) among reported Co-based alloys. Combined with experiments and theoretical calculation, the highly coupled interface between CoRu nanoalloy and Co s NC for strong electron-integration-boosting effect. This axial coupling precisely modulated the local coordination environment and electronegativity around surface Co s NC sites and formed new double active site (CoRu nanoalloy and Co s NC) for optimizing the activation kinetics of ammonia borane and water. This work provides in-depth insights into the mechanism of NH 3 BH 3 hydrolysis and paves a new way towards the high-efficient and stable heterogeneous catalysis. • A multiatomic active sites of bimetallic nanoalloy was constructed via solid-surfaces-situ-pyrolysis on Co s NC. • The accurate tailoring of Co s NC by out-of-plane alloy coupling attains a superior hydrogen production of NH 3 BH 3 hydrolysis. • Co 0.5 Ru 0.5 /Co s NC expresses an excellent activity with 1068 mol H2 mol Ru -1 min -1 and lowest activation energy of 18.96 kJ mol -1 . • The hydrogen production is significantly enhanced by electron-integration-boosting effect on alloy axial regulation. 

Out-of-plane CoRu nanoalloy axially coupling CosNC for electron enrichment to boost hydrogen production

Hydrogen (H2) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H2 production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H2 production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H2 production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H2 production, identifying the promising applications of controlled nanomaterials.

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Nanoengineering of Catalysts for Enhanced Hydrogen Production

Catalytic hydrolysis of ammonia borane (AB) provides an effective way to generate pure H2 at ambient temperature for fuel cells. Pt-based catalysts usually exhibit great initial activity toward this reaction but deactivate quickly. Here, we report that the metal-support interactions in Pt/Co3O4 nanocages can simultaneously accelerate the H2 generation and enhance the catalyst's stability. The Pt/Co3O4 catalyst is made for the first time by embedding Pt clusters (∼1.2 nm) in a high-surface-area Co3O4 nanocage to maximize the metal-support interface. The turnover frequency of the Pt/Co3O4 catalyst is about nine times higher than that of commercial Pt/C and outperforms almost all other Pt-based catalysts. X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, in situ spectroscopy, and density functional theory calculations suggest that the Co3O4 nanocages with rich oxygen vacancies facilitate the adsorption and dissociation of H2O to give electropositive H (Hδ+), while the in situ embedded Pt clusters can accelerate the formation of electronegative H (Hδ-) from AB. Subsequently, the Hδ+ and Hδ- spill over to the abundant interfacial sites and bond into H2. In addition to this dual-function synergy effect, the strong metal-support electronic interactions between Co3O4 and Pt benefit the desorption of poisonous B-containing byproducts from Pt sites. This effect together with cluster anchoring leads to a fivefold enhancement in durability compared to commercial Pt/C. The metal-support interactions revealed in this study provide more options for catalyst design toward facile H2 production from chemical hydrogen storage materials.

Jiankang Zhao

Papers

Maximizing Metal-Support Interactions in Pt/Co3O4 Nanocages to Simultaneously Boost Hydrogen Production Activity and Durability.