Graphene quantum dots (GQDs) are a promising category of materials with remarkable size dependent properties like tunable bandgap and photoluminescence along with the possibility of effective chemical functionalization. Doping of GQDs with heteroatoms is an interesting way of regulating their properties. Herein, we report a facile and scalable one-step synthesis of luminescent GQDs, substitutionally co-doped with N, F and S, of ∼2 nm average size by a microwave treatment of multi-walled carbon nanotubes in a customized ionic liquid medium. The use of an ionic liquid coupled with the use of a microwave technique enables not only an ultrafast process for the synthesis of co-doped GQDs, but also provides excellent photoluminescence quantum yield (70%), perhaps due to the interaction of defect clusters and dopants.

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Herein, we report a single step, anionic surfactant-assisted, low temperature-hydrothermal synthetic strategy of CoO nanoparticles anchored on β-Co(OH) nanosheets which show a low overpotential (295 mV @ 10 mA cm) for the oxygen evolution reaction (OER). They also demonstrate much better kinetic parameters compared to the state-of-the-art RuO. Interestingly, under the OER operational conditions (in alkaline medium), the topotactic transformation of α-Co(OH) to a stable Brucite-like β-Co(OH) phase leads to a synergistic interaction between the β-Co(OH) sheets on the CoO nanoparticles for enhancing the OER electrocatalytic activity.

Electrochemical water oxidation is a dynamic and basal approach for several energy conversion technologies such as solar fuels and metal–air batteries. Herein, we report a novel ‘nitrogen’ (N) enriched interconnected graphene quantum dots (C‐GQDs) as efficient oxygen evolution electrocatalyst, a potential candidate to replace the noble metal OER electrocatalysts. Interestingly, C‐GQDs deliver a current density of 10 mAcm‐2 at 350 mV, a small Tafel slope of 55 mV/dec and outstanding durability which is much superior to the state‐of‐the‐art precious RuO2. More precisely, the unexpected behaviour of graphene quantum dots towards oxygen evolution reaction (OER) is attributed to the interconnection through N‐rich framework (25 %) among the discrete particles. Predominantly, in the pyridine N‐oxide, N acts as nucleophilic site and pyridinic N develops p‐ type doping, responsible for enhanced the OER electrocatalytic activity. The co‐existence of both pyridinic N and pyridine N‐oxide N induces charge redistribution through π‐π delocalization to reduce the *OOH thermodynamic energy barrier. We hope that our study will encourage to develop more efficient electrocatalysts with more effective doping or surface functionalized structure by understanding the dopant nature.

Emerging energy storage systems based on abundant and cost-effective materials are key to overcome the global energy and climate crisis of the 21st century.

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Abstract Conventional inorganic semiconductor quantum dots (QDs) have numerous applications ranging from energy harvesting to optoelectronic and bio-sensing devices primarily due to their unique size and shape tunable band-gap and also surface functionalization capability and consequently, have received significant interest in the last few decades. However, the high market cost of these QDs, on the order of thousands of USD/g and toxicity limit their practical utility in many industrial applications. In this context, graphene quantum dot (GQD), a nanocarbon material and a new entrant in the quantum-confined semiconductors could be a promising alternative to the conventional toxic QDs due to its potential tunability in optical and electronic properties and film processing capability for realizing many of the applications. Variation in optical as well as electronic properties as a function of size, shape, doping and functionalization would be discussed with relevant theoretical backgrounds along with available experimental results and limitations. The review deals with various methods available so far towards the synthesis of GQDs along with special emphasis on characterization techniques starting from spectroscopic, optical and microscopic techniques along with their the working principles, and advantages and limitations. Finally, we will comment on the environmental impact and toxicity limitations of these GQDs and their hybrid nanomaterials to facilitate their future prospects. Graphical Abstract: Structure of doped, functionalized and hybrid GQDs

Herein, we report, a hybrid of mixed valent cobalt ludwigite (Co3BO5) and reduced‐multiwalled carbon nanotubes (R‐MWCNTs) as an outstanding oxygen evolution reaction (OER) electrocatalyst. Interestingly, the composite acts as a potential OER electrocatalyst, displaying a low overpotential of 270 mV @10 mA cm−2, which is lower than that for the state‐of‐the‐art RuO2 catalyst. The remarkable OER performance of the cobalt‐ludwigite is attributed to its basic distorted open crystal structure, which has a relatively high crystal volume, owing to a domain network consisting of edge‐sharing octahedra. Moreover, X‐ray photoelectron spectroscopy clarifies the hybrid of cobalt‐ludwigite and R‐MWCNTs, exhibiting a stable π‐cation‐like interaction between the Co3+ of Co3BO5 rather than Co2+ and neutral π‐ cloud of R‐MWCNTs, which helps in enhancing the conductivity of the system. Thus, the overall performance of the composite stems from the basic crystal structure of the Co3BO5 and the existence of synergistic effects between the R‐MWCNTs on Co3BO5 through π‐cation‐like interaction. Hence, the results of this study might be useful in developing more efficient other ludwigite–carbon OER electrocatalysts as affordable alternatives.