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Recently, metal‐free, heteroatom‐doped carbon nanomaterials have emerged as promising electrocatalysts for the oxygen evolution reaction (OER), but their synthesis is a tedious process involving energy‐wasting calcination. Molecular electrocatalysts offer attractive catalysts for the OER. Here, phytic acid (PA) was selected to investigate the OER activity of carbons in organic molecules by DFT calculations and experiments. Positively charged carbons on PA were very active towards the OER. The PA molecules were fixed into a porous, conductive hydrogel with a superhydrophilic surface. This outperformed most metal‐free electrocatalysts. Besides the active sites on PA, the high OER activity was also related to the porous and conductive networks on the hydrogel, which allowed fast charge and mass transport during the OER. Therefore, this work provides a metal‐free, organic‐molecule‐based electrocatalyst to replace carbon nanomaterials for efficient OER. Positively charged carbons on organic molecules (i.e. phytic acid, denoted PA) can participate in the oxygen evolution reaction (OER), as shown by DFT calculations and experiments. Moreover, doping of PA into a porous and conductive hydrogel is a robust strategy for stabilizing PA, as well as boosting the charge and mass transport of PA during the OER. [ABSTRACT FROM AUTHOR]

Recently, metal‐free, heteroatom‐doped carbon nanomaterials have emerged as promising electrocatalysts for the oxygen evolution reaction (OER), but their synthesis is a tedious process involving energy‐wasting calcination. Molecular electrocatalysts offer attractive catalysts for the OER. Here, phytic acid (PA) was selected to investigate the OER activity of carbons in organic molecules by DFT calculations and experiments. Positively charged carbons on PA were very active towards the OER. The PA molecules were fixed into a porous, conductive hydrogel with a superhydrophilic surface. This outperformed most metal‐free electrocatalysts. Besides the active sites on PA, the high OER activity was also related to the porous and conductive networks on the hydrogel, which allowed fast charge and mass transport during the OER. Therefore, this work provides a metal‐free, organic‐molecule‐based electrocatalyst to replace carbon nanomaterials for efficient OER. [ABSTRACT FROM AUTHOR]

Ultrathin nanomeshes perfectly inherit the integrated advantages of ultrathin 2D materials and porous nanostructures, which have shown their great application potential in catalysis and electronic devices. Here, the general synthesis of ultrathin metal borate (i.e., Co‐Bi, Ni‐Bi, and Fe‐Bi) nanomeshes is reported by capitalizing on 3D bark‐like N‐doped carbon (denoted BNC) as nanoreactors. Indeed, this strategy is straightforward, only comprising a one‐step reaction between metal cations and sodium borohydride without using templates. As nanoreactors, the BNC derived from biomass waste of lychee exocarp possesses distinctive advantages of low cost, fractured textures, porous nanostructures (surface area: 1915.5 m2 g−1), electronegative surface (zeta potential: −43.4 mV), and superhydrophilicity for greatly facilitating the adsorption of metal cations with strong strength to effectively control the growth of 2D nanomeshes. The as‐synthesized Co‐Bi and Ru‐doped Co‐Bi (Ru‐Co‐Bi) nanomeshes exhibit excellent performance for the oxygen evolution reaction and hydrogen evolution reaction, respectively. Impressively, the water splitting device based on the Co‐Bi and Ru‐Co‐Bi nanomeshes can enable a current density of 10 mA cm−2 at a small cell voltage of 1.53 V. Therefore, this work paves new avenues for the facile synthesis of ultrathin metal nanomeshes. [ABSTRACT FROM AUTHOR]

Despite the exciting achievements made in synthesis of monofunctional electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), or hydrogen evolution reaction (HER), it is challenging to develop trifunctional electrocatalysts for both ORR/OER/HER. Herein, N, O‐codoped graphene nanorings‐integrated boxes (denoted NOGB) are crafted via high‐temperature pyrolysis and following acid etching of hybrid precursors containing polymers and Prussian blue analogue cubes. The electrochemical results signified that the resulting NOGB‐800 (800 refers to pyrolysis temperature) is highly active for trifunctional electrocatalysis of ORR/OER/HER. This can be reasonably attributed to the advanced nanostructures (i.e., the hierarchically porous nanostructures on the hollow nanorings) and unique chemical compositions (i.e., N, O‐codoped graphene). More attractively, the rechargeable Zn–air battery based on NOGB‐800 displays maximum power density of 111.9 mW cm−2 with small charge–discharge potential of 0.72 V and excellent stability of 30 h, comparable with the Pt/C+Ir/C counterpart. The NOGB‐800 could also be utilized as bifunctional electrocatalysts for overall water splitting to yield current density of 10 mA cm−2 at a voltage of 1.65 V, surpassing most reported electrocatalysts. Therefore, the NOGB‐800 is a promising candidate instead of precious metal–based electrocatalysts for the efficient Zn–air battery and water splitting. An easy yet robust route, for the first time, is developed to craft N, O‐codoped graphene‐integrated boxes by employing hybrids containing polymers and Prussian blue analogue cubes as precursors. Benefiting from the hierarchically porous nanostructures and highly active N, O‐codoped graphene, the resulting electrocatalysts display excellent performance on the overall water splitting and Zn–air battery. [ABSTRACT FROM AUTHOR]

The ability to develop bifunctional electrocatalysts for concurrent CO2 reduction reaction (CO2RR) and oxygen evolution reaction (OER) is the key to the practical application of CO2 splitting to produce CO. However, this remains a grand challenge. Herein, a robust strategy to rationally craft hierarchical structured bifunctional electrocatalysts composed of 3D CoS2 nanocages interconnected on 2D CoS2 nanosheet arrays (denoted hierarchical CoS2 nanocages) for high‐performance CO2 splitting is developed. The subsequent calcination removes the partial S edges of CoS2, thereby strongly suppressing the hydrogen evolution reaction (HER) of CoS2. By combining theoretic and experimental results, for the first time, it is discovered that the plane S of CoS2, instead of S edges, are highly active for CO2RR but inactive for HER, rendering the plane S as ideal active sites for CO2RR. Intriguingly, the composition tuning via calcination and the presence of a hierarchical architecture confer hierarchical CoS2 nanocages respective outstanding CO2RR and OER performance. Notably, the hierarchical CoS2 nanocages can be exploited as bifunctional electrocatalysts for overall CO2 splitting to yield the current density of 1 mA cm−2 at a small cell voltage of 1.92 V, much lower than the widely reported values (>2.5 V). [ABSTRACT FROM AUTHOR]