Exceptional activity of amino-modified rGO-immobilized PdAu nanoclusters for visible light-promoted dehydrogenation of formic acid

Formic acid(FA),which is obtainable through CO_(2)hydrogenation with green hydrogen or biomass conversion,has been used as a prospective liquid organic hydrogen carrier(LOHC)because of the abundant advantages of renewability,wide availability,stability,and high volumetric capacity(53 g H_(2)/L).The development of highly efficient catalytic systems to achieve enhanced catalytic activity is attractive but still challenging.Herein,ultrafine and highly dispersed PdAu nanoclusters(NCs)anchored on amino-modified reduced graphene oxide(ArGO)were successfully synthesized via a facile impregnation-reduction method and applied as a catalyst toward formic acid dehydrogenation(FAD).Benefiting from the promoting effect of amino groups,the strain and ligand effect in the alloy,and the Mott–Schottky effect between PdAu NCs and ArGO,the resultant PdAu/ArGO affords an ultrahigh activity under visible light irradiation with an exceptional turnover frequency value of 10,699.5 h^(-1)at 298 K without any additives,more than 2.6times improvement than that under dark,which is the highest among all reported catalysts under the same conditions.This study provides a green and convenient strategy for developing more efficient and sustainable FAD catalysts and promotes the effective utilization of FA as a prospective renewable LOHC.

A step‐growth strategy to grow vertical porous aromatic framework nanosheets on graphene oxide:Hybrid material‐confined Co for ammonia borane methanolysis

The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth strategy is developed to fabricate a vertically oriented nitrogen-rich porous aromatic framework on graphene oxide(V-PAF-GO)using monolayer benzidine-functionalized GO(BZ-GO)as a molecular pillar.Then,the confined Co nanoparticle(NP)catalysts are synthesized by encapsulating ultra-small Co into the slit pores of V-PAF-GO.Due to the high nitrogen content,large specific surface area,and adequate slit pores,the optimized vertical nanocomposites V-PAF-GO provide abundant anchoring sites for metal NPs,leading to ultrafine Co NPs(1.4 nm).The resultant Co/V-PAF-GO catalyst shows an extraordinary catalytic activity for ammonia borane(AB)methanolysis,yielding a turnover frequency value of 47.6 min−1 at 25°C,comparable to the most effective non-noble-metal catalysts ever reported for AB methanolysis.Experimental and density functional theory studies demonstrate that the electron-donating effect of N species of PAF positively corresponds to the low barrier in methanol molecule activation,and the cleavage of the O–H bond in CH3OH has been proven to be the rate-determining step for AB methanolysis.This work presents a versatile step-growth strategy to prepare a vertically oriented PAF on GO to solve the stacking problem of 2D materials,which will be used to fabricate other novel 2D or 2D–2D materials with controllable orientation for various applications.

Y_(2)O_(3)-functionalized graphene-immobilized Ni–Pt nanoparticles for enhanced hydrous hydrazine and hydrazine borane dehydrogenation

Developing efficient and highly selective catalyst to promote hydrogen generation from hydrous hydrazine(N_(2)H_(4)·H_(2)O) and hydrazine borane(N_(2)H_(4)BH_(3))remains a challenging issue for fuel cell-based hydrogen economy.In this work,ultrafine and well-dispersed bimetallic NiPt nanoparticles(3.4 nm) were successfully immobilized on Y_(2)O_(3)-functionalized graphene(Y_(2)O_(3)/rGO) without any surfactant by a simple liquid impregnation approach.It is firstly found that integration of graphene and Y_(2)O_(3) not only can facilitate the formation of ultrafine NiPt nanoparticles(NPs),but also can effectively modulate the electronic structure of NiPt NPs,thereby boosting the catalytic performance.Compared with NiPt/Y_(2)O_(3) and NiPt/rGO,the NiPt/Y_(2)O_(3)/rGO nanocomposites(NCs) show remarkable enhanced catalytic efficiency for hydrogen production from N_(2)H_(4)-H_(2)O.In particular,the optimized Ni_(0.6)Pt_(0.4/)Y_(2)O_(3)/rGO NCs display the best catalytic efficiency and 100% H_(2) selectivity for N_(2)H_(4)-H_(2)O dehydrogenation,providing a turnover frequency(TOF) of2182 h^(-1) at 323 K,which is among the highest values ever reported.Moreover,the Ni_(0.6)Pt_(0.4)/Y_(2)O_(3)/rGO NCs also exhibit an excellent catalytic performance(TOF=3191 h^(-1)) and 100% H_(2) selectively for N_(2)H_(4)BH_(3)dehydrogenation at 323 K.The outstanding catalytic results obtained provide more possibilities for the potential applications of N_(2)H_(4)·H_(2)O and N_(2)H_(4)BH_(3) as promising chemical hydrogen storage materials.

Hydrogen production from chemical hydrogen storage materials over copper-based catalysts

Hydrogen,as a clean and efficient energy source,is one of the important energy carriers in the future.However,the safe storage and delivery of hydrogen is still a bottleneck in its practical applications.Chemical hydrides(such as NaBH_(4),NH_(3)BH_(3),N_(2)H_(4)·H_(2)O,N_(2)H_(4)BH_(3),and HCOOH)are considered as potential chemical hydrogen storage materials that can achieve rapid on-site hydrogen production.At present,the most critical issue for them is to develop economic catalysts to achieve efficient hydrogen production from chemical hydrides.Cop-per(Cu)is considered as a promising catalyst that is one of the most reactive metals among the first-row transition metals and economically cheap.In this review,we outline the recent advancements of Cu-based catalysts in catalyzing hydrogen production from chemical hydrides.Moreover,the synthesis methods,characterization techniques,and hydrogen production catalytic activity of Cu-based catalysts were also introduced.Finally,a brief conclusion and outlook are given for the application of Cu-based catalysts in the dehydrogenation of chemical hydrides.We hope that this review will stimulate interest in the promising research area of Cu-based catalysts for the dehydrogenation of chem-ical hydrides.