A deep understanding of the electricity generation mechanism from the interaction between water molecules and carbon material surfaces is attractive for next-generation water-based energy conversion and storage systems. Herein, an asymmetric generator was assembled based on functionalized carbon nanotubes films to investigate the relative contribution from various oxygen functional groups on carbon surface to the water-electrical performance. Experiments and calculations demonstrate that the electricity mainly originates from the water molecule adsorption by carboxyl groups and dissociation of functional groups on carbon surface, which leads to the formation of electrical double layers at interfaces. This device allows the electricity generation with a variety of water sources, such as deionized water, tap water, as well as seawater. In particular, the generator based on carboxyl carbon nanotubes can induce a voltage of over 200 mV spontaneously in natural seawater with the power density of about 0.11 mW·g⁻¹. High voltages can be achieved easily through the series-connection strategy to power electronic products such as a liquid crystal display. This work reveals the dominant role of carboxyl groups in carbon-based water–electricity conversion and is expected to offer inspiration for the preparation of carbon materials with high electrical performance.

Solar-driven interfacial evaporation (SDIE) is emerging as a promising pathway to solving the worldwide water shortage and water pollution. Nanomaterials (e.g., plasmonic metals, inorganic/organic semiconductors, and carbon nanomaterials) and related nanochemistry have attracted increasing attention for the solar-to-vapor process in terms of broadband absorption, electronic structure adjustment, and surface/interface chemistry manipulation. Furthermore, the assembly of nanomaterials can contribute to the mass transfer, heat management, and enthalpy regulation of water during solar evaporation. To date, numerous nano-enabled materials and structures have been developed to improve the solar absorption, heat management (i.e., heat confinement and heat transfer), and water management (i.e., activation, evaporation, and replenishment). In this review, we focus on a systematical summary about the composition and structure engineering of nanomaterials in SDIE, including size and morphology effects, nanostructure optimizations, and structure-property relationship decoupling. This review also surveys recent advances in nanochemistry (e.g., preparation chemistry and structural chemistry) deployed to conceptual design of nanomaterials. Finally, the key challenges and future perspectives of nanomaterials for solar evaporation are overviewed. This review aims at providing guidance for the design and construction of nanomaterials for high-efficiency SDIE on the basis of the aspects of materials science and chemical engineering.

Metal–organic framework (MOF)-derived carbon composites have been considered as the promising materials for energy storage. However, the construction of MOF-based composites with highly controllable mode via the liquid–liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase. Herein, we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates, including carbon nanotubes (CNTs), graphene oxide (GO), MXene, layered double hydroxides (LDHs), MOFs, and SiO₂. The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity (V_meso/V_micro: 2.4), ultrahigh N content of 12.4 at.% and “dual electrical conductive networks.” The assembled aqueous zinc-ion hybrid capacitor (ZIC) with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g⁻¹ at 0.5 A g⁻¹, great rate performance of 98 F g⁻¹ at 100 A g⁻¹, and especially, an ultralong cycling stability up to 230000 cycles with the capacitance retention of 90.1%. This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.

As one of carbon nanomaterials, carbon dots have attracted widespread attention due to their ultra-small size, abundant surface functional groups, good chemical stability, and superior optoelectronic properties. In this review, the structures, classifications, characteristics, and preparation methods of carbon dots were introduced. Recent research studies on carbon dots as various components or additives in dye-sensitized solar cells were represented. The challenges of controllable synthesis, structure-property relationship, and performance optimization of carbon dots were analyzed. In addition, the development directions of large-scale controllable preparation for carbon dots and their application in dye-sensitized solar cells were proposed.

Heteroatom doping carbon materials exhibit a huge application potential for energy storage devices (ESDs). Herein, interconnected N/P co-doped carbon nanocage (NP-CNC) was synthesized from pyrene molecules by using nano-MgO as template and melamine-phytic acid supramolecular aggregate as dopant coupled with KOH activation. The as-prepared NP-CNC possesses interconnected nanocages for electron transportation and abundant micropores for ion adsorption. Moreover, co-doped N/P species in NP-CNC provide active sites and additional pseudocapacitance. Consequently, NP-CNC as electrode material for symmetric supercapacitor exhibits a high gravimetric capacitance of 435 F·g⁻¹ at 0.05 A·g⁻¹, high volumetric capacitance of 274 F·cm⁻³ at 0.032 A·cm⁻³, and long cycle lifespan with 96.1% capacitance retention after 50,000 cycles. Furthermore, NP-CNC as cathode for zinc-ion hybrid supercapacitor delivers satisfactory energy and power densities of 130.6 Wh·kg⁻¹ (82.3 Wh·L⁻¹) and 14.4 kW·kg⁻¹ (9.1 kW·L⁻¹). This work paves a promising approach to the preparation of high capacitance NP-CNC for ESDs.