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Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C₃N₄). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C₃N₄. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization.

Novel sulfur (S) anchoring materials and the corresponding mechanisms for suppressing capacity fading are urgently needed to advance the performance of Li/S batteries. Here, we designed and synthesized a graphene-like oxygenated carbon nitride (OCN) host material that contains tens of micrometer scaled two-dimensional (2D) rippled sheets, micromesopores, and oxygen heteroatoms. N content can reach as high as 20.49 wt %. A sustainable approach of one-step self-supporting solid-state pyrolysis (OSSP) was developed for the low-cost and large-scale production of OCN. The urea in solid sources not only provides self-supporting atmospheres but also produces graphitic carbon nitride (g-C3N4) working as 2D layered templates. The S/OCN cathode can deliver a high specific capacity of 1407.6 mA h g(-1) at C/20 rate with 84% S utilization and retain improved reversible capacity during long-term cycles at high current density. The increasing micropores, graphitic N, ether, and carboxylic O at the large sized OCN sheet favor S utilization and trapping for polysulfides.

A natural self-regeneration step for urea derived graphitic carbon nitride with platinum nanoparticles is found by simply opening the system to air in the dark under ambient conditions, following its solar-driven hydrogen production. The produced peroxides deactivate the graphitic carbon nitride. Release of weakly bound peroxides on the polymeric semiconductor surface is a crucial process for regeneration.

A RGO/CNT hybrid electrode of porous structure is prepared through a surfactant-free solution method to construct a bimorph ionic actuator, showing wide frequency range responsive and highly repeatable (over a million times) and stable bending actuation performance.

Developing new methods to improve the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) for hydrogen (H₂) evolution has attracted intensive research interests. Here, we report that the g-C₃N₄ exhibits photocatalytic activity for H₂ evolution from pure water. And, the activity is dramatically improved by loading highly dispersed conductive polymer nanoparticles. The H₂ evolution rate increases up to 50 times for g-C₃N₄ with 1.5 wt% polypyrrole (PPy) nanoparticles on the surface. The reaction proceeding in a pure water system excludes the need for sacrificial agents. The role of the highly conductive PPy in enhancing H₂ evolution is as a surface junction to increase the number of photoinduced electrons, and to facilitate electron transfer to the interface.

This paper reports novel electromechanical behavior for a natural biopolymer film due to the incorporation of a conductive carbon nanotube network. Through simple solution blending and casting, high weight fraction single-walled carbon nanotube-chitosan composite films were fabricated and exhibited electromechanical actuation properties with motion controlled by low alternating voltage stimuli in atmospheric conditions. Of particular interest and importance is that the displacement output imitated perfectly the electrical input signal in terms of frequency (<10 Hz) and waveform. Operational reliability was confirmed by stable vibration testing in air for more than 3000 cycles. Proposed electrothermal mechanism considering the alternating current-induced periodic thermal expansion and contraction of the composite film was discussed. The unique actuation performance of the carbon nanotube-biopolymer composite, coupled with ease of fabrication, low driven voltage, tunable vibration, reliable operation, and good biocompatibility, shows great possibility for implementation of dry actuators in artificial muscle and microsystems for biomimetic applications.

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