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The development of single-atom catalysts anchored on two-dimensional (2D) conductive matrix with well exposed active sites has great significance in electrocatalytic energy storage yet remains challenging. Inspired by the power of biomolecular self-assembly in making delicate nanostructures, we report a novel template-free folic acid (FA) self-assembly strategy to achieve the facile preparation of ultrathin N-doped carbon nanosheet confining single-metal-atom catalysts (M-N-C SAC, M = Co, Ni, Zn, Fe). The 2D association of FA is developed for the first time via the ribbon-like H bonding pattern and metal-FA coordination in a mixed solvent. A tunable metal loading content of the catalysts is facilely realized through a pH-tuned FA partial dissociation chemistry. As a proof of demonstration, Co-N-C SAC shows an excellent performance for lean electrolyte lithium-sulfur battery. Our findinging suggest a new and potentially scalable route for facile fabrication of M-N-C SACs for broad energy storage applications.

Numerous scientists are in the pursuit of energy storage materials with high energy and high power density by assembly of electrochemically active materials into conductive scaffolds, owing to the emerging need for next-generation energy storage devices. In this architectures, the active materials bonded to the conductive scaffold can provide a robust and free-standing structure, which is crucial to the fabrication of materials with high gravimetric capacity. Thus, hierarchical copper-cobalt-nickel ternary oxide (CuCoNi-oxide) nanowire arrays grown from copper foam were successfully fabricated as free-standing anode materials for lithium ion batteries (LIBs). CuCoNi-oxide nanowire arrays could provide more active sites owing to the hyperbranched structure, leading to a better specific capacity of 1191 mAh/g, cycle performance of 73% retention in comparison to CuO nanowire structure, which exhibited a specific capacity of 1029 mAh/g and capacity retention of 43%, respectively.

Biomolecules with a broad range of structure and heteroatom-containing groups offer a great opportunity for rational design of promising electrocatalysts via versatile chemistry. In this study, uniform folic acid–Co nanotubes (FA–Co NTs) were hydrothermally prepared as sacrificial templates for highly porous Co and N co-doped carbon nanotubes (Co–N/CNTs) with well-controlled size and morphology. The formation mechanism of FA–Co NTs was investigated and FA–Co-hydrazine coordination interaction together with the H-bond interaction between FA molecules was characterized to be the driving force for growth of one-dimensional nanotubes. Such distinct metal–ligand interaction afforded the resultant CNTs rich Co–Nx sites, hierarchically porous structure and Co nanoparticle-embedded conductive network, thus an overall good electrocatalytic activity for oxygen reduction. Electrochemical tests showed that Co–N/CNTs-900 promoted an efficient 4e− ORR process with an onset potential of 0.908 V vs. RHE, a limiting current density of 5.66 mA cm−2 at 0.6 V and a H2O2 yield lower than 5%, comparable to that of 20% Pt/C catalyst. Moreover, the catalyst revealed very high stability upon continuous operation and remarkable tolerance to methanol.

γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al (aluminum) - air batteries. The rich oxygen vacancies on the surface of γ-MnO2 are verified by morphology, structure, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) results. The oxygen reduction reaction (ORR) electrocatalytic activity of γ-MnO2 is significantly improved by the incoming oxygen vacancies. The γ-MnO2 nanorod-assembled hierarchical micro-spheres calcined under 300 °C in Ar atmosphere show the best ORR performance. The primary Al-air batteries using γ-MnO2 catalysts as the cathode, which demonstrates excellent peal power density of 318 mW cm−2 when applying the γ-MnO2 catalysts with optimal amount of oxygen vacancies.

Metal nanoparticles stabilized on a support material have been explored extensively to boost heterogeneous catalysis. Herein, the effect of metal-support interaction between bismuth (Bi) nanoparticles and reduced graphene oxide nanosheets (Gr) on the electroreduction of CO2 towards value-added formate is explored. The obtained Bi/Gr hybrid catalysts exhibit a superior catalytic activity towards electrochemical reduction of CO2, which gives the maximum faradic efficiency of 92.1 % at -0.97 V (vs. RHE) for formate generation. Particularly, the hydride shows an enhancement to the catalysts of bare Bi and physical mixture of Bi and Gr, with a high current density of 28.1 mA∙cm−2 and production rate of 0.53 mol∙cm−2 h-1 at -1.17 V (vs. RHE) for formate generation. The electrochemical analysis reveals that the metal-support interactions substantially boost CO2 electroreduction activity through modification the electronic structure and improving interfacial electron transfer between Bi and Gr. This work not only deepens an understanding of metal-support interaction effect but also sheds light on the design of high-efficiency catalysts toward CO2 electroreduction by virtue of the interactions between active metals and carbon-like support.

Interfaces of metal-oxide heterostructured electrocatalyst are critical to their catalytic activities due to the significant interfacial effects. However, there are still obscurities in the essence of interfacial effects caused by crystalline defects and mismatch of electronic structure at metal-oxide nanojunctions. To deeply understand the interfacial effects, we engineered crystalline-defect Pd-Cu2O interfaces through non-epitaxial growth by a facile redox route. The Pd-Cu2O nanoheterostructures exhibit much higher electrocatalytic activity toward glucose oxidation than their single counterparts and their physical mixture, which makes it have a promising potential for practical application of glucose biosensors. Experimental study and density functional theory (DFT) calculations demonstrated that the interfacial electron accumulation and the shifting up of d bands center of Cu-Pd toward the Fermi level were responsible for excellent electrocatalytic activity. Further study found that Pd(3 1 0) facets exert a strong metal-oxide interface interaction with Cu2O(1 1 1) facets due to their lattice mismatch. This leads to the sinking of O atoms and protruding of Cu atoms of Cu2O, and the Pd crystalline defects, further resulting in electron accumulation at the interface and the shifting up of d bands center of Cu-Pd, which is different from previously reported charge transfer between the interfaces. Our findings could contribute to design and development of advanced metal-oxide heterostructured electrocatalysts.

While increasing worldwide energy consumption demands for better storage devices, the environmental impact of these is often neglected. More sustainable energy storage in terms of greener battery materials would be desirable. In this regard, bioderived quinone containing molecules may serve as active battery material. Here, dopamine, among others an important neurotransmitter or active in mussel adhesion, is copolymerized with pyrrole to form a rod-like mixed copolymer. n-type charge storage in the quinone functionalities is combined with p-type charge storage in the conjugated doped polymer backbone from pyrrole and dopamine units with decreased polaron delocalization length compared to neat polypyrrole. The resulting sustainable polymer can be used as a cathode material due to a favorable redox potential of approx. 3.0–3.5 V vs. Li+/Li. It can reversibly store 160 mA h g−1 at a discharging rate of 100 mA g−1 and hence achieve similar capacities than inorganic, unsustainable, cathode materials and significantly higher capacities than other sustainable cathodes. Capacity is stable for more than 50 cycles, and even at high discharging rate of 800 mA g−1, approximately 90 mA h g−1 are reversibly stored with coulombic efficiency of almost 100%.

Developing high-efficient and durable electrocatalysts for CO2 electroreduction reaction (CO2RR) at high current density is attractive but still challenging. In this study, ultrasmall Bi nanoparticles confined in carbon nanosheets are successfully prepared by directly annealing of dipped carbon cloth. Benefited from the uniform distribution of the ultrasmall Bi nanoparticles and the in‐situ‐formed carbon nanosheets, the resultant self-supported electrocatalysts exhibit excellent CO2RR activity in a synergistic way. The optimized Bi-PVP/CC600 exhibits high formate faradaic efficiency of over 81 % at high current densities in a wide potential range. Impressively, high durability is also achieved for this binder-free electrode, with a remarkable high current density of 54 mA∙cm−2 for nearly 40 h. The high performance associated with this facile and potentially scalable synthetic method suggests the great application potential of ultrasmall Bi nanoparticles in CO2RR. The strategy developed herein is versatile and can be extended to prepare other high‐performance ultrasmall metal nanoparticles catalysts.

Electro-oxidative organic upgrading is recently considered as a promising strategy for energy saved H2 co-generation but still challenging for high productivity of value-added chemicals at large current density. Herein, the synthesized defects-rich Ni3S2-CNFs nanoheterostructures exhibit robust electrocatalytic performance for selectively catalyzing methanol to value-added formate with high productivity and without CO2 emission, in which the large current density (> 700 mA cm−2) is achieved with high faradaic efficiency (> 90%). By replacing the sluggish OER, the methanol upgrading reaction can greatly boost H2 co-generation from water with reduced energy consumption. DFT calculations indicate the in situ formed Ni–OOH and SOx species with synergistic effect can effectively modulate the d band center of Ni3S2 in Ni3S2-CNFs nanoheterostructures, acting as unique collaborative active sites for the thermodynamically favorable conversion from methanol to formate and suppressing the further oxidation to CO2, resulting in the high activity and selectivity of CO2-emission-free methanol upgrading reaction.

Solid oxide cells (SOCs) including solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are advanced electrochemical energy storage and conversion devices. However, the lack of highly active and stable fuel electrode materials impedes their practical applications. Herein, in-situ exsolved CoFe nanoparticles on perovskite matrixes with abundant defects are developed as bifunctional fuel electrocatalysts for SOCs from the Sr2FeMo1-xCoxO6−δ (x = 0, 0.15, 0.25, 0.45) precursor. Increasement of Co doping promotes CoFe alloy exsolution and the formation of more defects in the remaining perovskite matrix under reducing atmosphere at high temperatures. Consequently, with increasing Co dopant content, the electrocatalytic activity towards CO2 electrolysis and hydrogen (H2) fuel oxidation are both significantly enhanced for the reduced Sr2FeMo1-xCoxO6−δ. The reduced Sr2FeMo1-xCoxO6−δ with high Co doping content of x = 0.45 electrocatalysts also exhibits respectable coking resistance and excellent long-term stability. The high performance may be owing to the unique simultaneously in-situ formed nanoalloy-oxide heterostructure and electron-ion mixed conductive perovskite matrixes with abundant defects.

A simple approach was developed to synthesize the three-dimensional (3D) hybrid of manganese dioxide (MnO 2 ) and graphene foam. The morphology of the MnO 2 nanostructures can be readily controlled by the solution acidity. Furthermore, we demonstrate that, serving as a free-standing supercapacitor electrode, this novel three-dimensional hybrid gives a remarkable specific capacitance (560 F/g at the current density of 0.2 A/g) and excellent cycling stability.