Metal-organic frameworks (MOFs) and MOF-derived materials have recently attracted considerable interest as alternatives to noble-metal electrocatalysts. Herein, the rational design and synthesis of a new class of Co@N-C materials (C-MOF-C2-T) from a pair of enantiotopic chiral 3D MOFs by pyrolysis at temperature T is reported. The newly developed C-MOF-C2-900 with a unique 3D hierarchical rodlike structure, consisting of homogeneously distributed cobalt nanoparticles encapsulated by partially graphitized N-doped carbon rings along the rod length, exhibits higher electrocatalytic activities for oxygen reduction and oxygen evolution reactions (ORR and OER) than that of commercial Pt/C and RuO , respectively. Primary Zn-air batteries based on C-MOF-900 for the oxygen reduction reaction (ORR) operated at a discharge potential of 1.30 V with a specific capacity of 741 mA h g under 10 mA cm . Rechargeable Zn-air batteries based on C-MOF-C2-900 as an ORR and OER bifunctional catalyst exhibit initial charge and discharge potentials at 1.81 and 1.28 V (2 mA cm ), along with an excellent cycling stability with no increase in polarization even after 120 h - outperform their counterparts based on noble-metal-based air electrodes. The resultant rechargeable Zn-air batteries are used to efficiently power electrochemical water-splitting systems, demonstrating promising potential as integrated green energy systems for practical applications.

Solid‐state aqueous energy conversion and storage are regarded as one of the most promising energy technologies for low‐cost and large‐scale applications without safety risk. However, current solid‐state aqueous batteries can only sustain tens to hundreds of charging–discharging cycles and deliver limited capacities, particularly in alkaline electrolytes. This has severely limited solid‐state energy technologies for large‐scale applications. Herein, it is reported that a sodium polyacrylate hydrogel electrolyte ensures an order of magnitude higher cycling stability than those of their state‐of‐the‐art counterparts and high capacities for the solid‐state Zn//NiCo and Zn–air batteries. The observed superb cell performance is attributed to a high ionic conductivity and water‐retaining capability intrinsically associated with the sodium polyacrylate hydrogel electrolyte, coupled with the acrylate‐ion‐facilitated formation of quasi‐solid electrolyte interface to eliminate zinc dendrites.

Buckminsterfullerene (C60) was adsorbed onto single-walled carbon nanotubes (SWCNTs) as an electron-acceptor to induce intermolecular charge-transfer with the SWCNTs, leading to a class of new metal-free C60-SWCNT electrocatalysts. For the first time, these newly developed C60-SWCNTs were demonstrated to act as trifunctional metal-free catalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) over a wide range of pH values, from acid to alkaline, with even higher electrocatalytic activities and better long-term stabilities than those of commercial Pt and RuO2 counterparts. Thus, the adsorption-induced intermolecular charge-transfer with the C60 electron-acceptor can provide a general approach to high-performance, metal-free, pH-universal carbon-based trifunctional metal-free electrocatalysts for water-splitting and beyond.

This article provides a timely and critical review on carbon-based metal-free catalysts for various electrocatalytic reactions, along with the mechanistic and structure–property relationship understanding, current challenges, and future perspectives.

Edge functionalization by selectively attaching chemical moieties at the edge of graphene sheets with minimal damage of the carbon basal plane can impart solubility, film-forming capability, and electrocatalytic activity, while largely retaining the physicochemical properties of the pristine graphene. The resultant edge-functionalized graphene materials (EFGs) are attractive for various potential applications. Here, a focused, concise review on the synthesis of EFGs is presented, along with their 2D covalent organic polymer (2D COP) analogues, as energy materials. The versatility of edge-functionalization is revealed for producing tailor-made graphene and COP materials for efficient energy conversion and storage.