Recent Progress of Metal Organic Frameworks-Based Electrocatalysts for Hydrogen Evolution,Oxygen Evolution,and Oxygen Reduction Reaction

Exploring efficient and cost-saving electrocatalysts is essential to the renewable energy storage and utilization,which is still in its embryonic period.MOFs have drawn tremendous attention due to their adjustability,abundant active sites,and plentiful pores.Notably,satisfactory electrocatalytic performance has been achieved by MOFs-based electrocatalysts comparable to traditional electrocatalysts.State-of-the-art works about the MOFs-based electrocatalysts for hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and ORR were summarized in this review.This review comprises a series of modifying strategies of MOFs and their derivatives,from aspects of structure,composition,and morphology.Furthermore,the active sites and functional mechanisms’recognition are involved in this review expecting to provide reference for rationally designing efficient electrocatalysts.At last,the current status,challenges,and perspectives of MOFs-based electrocatalysts are also discussed.

Bulky Thiolate-Protected Silver Nanocluster Ag_(213)(Adm-S)_(44)Cl_(33)with Excellent Electrocatalytic Performance toward Oxygen Reduction

Atomically precise gold and/or silver nanoclusters play a key role in crystallography and coordination chemistry.Compared with gold nanoclusters,silver nanoclusters become unstable and difficult to crystallize due to the high reactivity ofmetal silver.Herein,we report a silver nanocluster Ag_(213)(Adm-S)_(44)Cl_(33)(Ag_(213))coprotected by bulky thiolates and chlorides.The low surface thiolate coverage(about 45%)endows Ag_(213)with high catalytic activity.Supported on activated carbon,Ag_(213)nanoclusters exhibit excellent electrocatalytic oxygen reduction performance with Eonset and E_(1/2)values of 0.89 and 0.72 V,respectively,close to the values of commercial Pt/C catalyst.This is the first report on the electrocatalytic oxygen reduction reaction of nanoclusters with more than 100 silver atoms.Ag_(213)with the diameter of 2.75 nm comprises a core–shell structure Ag_(7)@Ag_(32)@Ag_(77)@Ag_(97).The strong plasmonic absorption band at 454 nm reveals the metallic nature of Ag_(213).Interestingly,halide is of importance.Chloride facilitates the formation of Ag_(213)and Ag_(56)(Adm-S)_(33)Cl_(16)(Ag_(56)^(Cl))while bromide can promote the formation of Ag_(56)(Adm-S)_(33)Br_(16)(Ag_(56)Br).This work provides an example for the study of largesized metal nanoclusters and nanocluster-based electrocatalysts.

Single-atomic Fe anchored on hierarchically porous carbon frame for efficient oxygen reduction performance

Exploring platinum group metal-free electrocatalysts with superior catalytic performance and favorable durability for oxygen reduction reaction is a remaining bottleneck in process of developing sustainable techniques in energy storage and conversion. Herein, a hierarchical porous single atomic Fe electrocatalyst(Fe/Z8-E-C) is rationally designed and synthesized via acid etching, calcination, adsorption of Fe precursor and recalcination processes. This unique electrocatalyst Fe/Z8-E-C shows excellent oxygen reduction performance with a half-wave potential of 0.89 V in 0.1 mol/L KOH, 30 m V superior to that of commercial Pt/C(0.86 V), which is also significantly higher than that of typical Fe-doped ZIF-8 derived carbon nanoparticles(Fe/Z8-C) with a half-wave potential of 0.84 V. Furthermore, Fe/Z8-E-C-based Zn-air battery exhibits greatly enhanced peak power density and specific capacity than those of original Fe/Z8-C,verifying the remarkable performance and practicability of this specially designed hierarchical structure due to its efficient utilization of the active sites and rapid mass transfer. This present work proposes a new method to rationally synthesize single atom electrocatalysts loaded on hierarchical porous frame materials for catalysis and energy conversion.