This paper reports a facile fabrication of N‐doped graphene quantum dots (N‐GQDs) showing controllable chemical properties through a hydrothermal treatment. The N‐GQDs have a uniform size of 3.06 ± 0.78 nm and prefer the equilibrium shapes of circle and ellipse due to the minimization of edge free energy. The N/C atomic ratio in N‐GQDs can be precisely tailored in a range from 8.3 at% to 15.8 at% by simply controlling the concentration of N source (ammonium hydroxide). One order of magnitude quantum yield of 34.5% is achieved by N‐GQDs, compared with the N‐free GQDs, as the substitutional N has an essential role in more effective radiative emission. Excessive N dopants in N‐GQDs can lead to photoluminescence quenching, through nonradiative transition back to the ground state. The N‐GQDs are further found to be suitable as photocurrent conversion materials due to benign energy matching with anatase nanofibers, the ultrafast electron injection at their interface, and efficient electron transfer. This work provides an efficient and inspiring approach to engineering both chemical components and physical properties of N‐GQDs, and will therefore promote their basic research and applications in energy conversion.

A photo-, acid- and thermo-responsive nitrobenzene-based amphiphilic copolymer was synthesized and the corresponding multi-responsive behavior of the copolymer assemblies was revealed by TEM, DLS and AFM. The morphological changes of the assemblies under multi-stimuli endowed them with a controlled release of encapsulated molecules.

Broadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) have many prospective applications in areas related to food inspection, health management, plant growth, and night vision, because NIR phosphors are critical components of the corresponding devices. Given the wide‐ranging applicability of the material, this study is designed to comprehensively evaluate a series of novel NIR phosphors: BaMgGaxAl10–xO17:Cr3+ (x = 0, 1, 2, 3). The ultra‐low‐temperature (4 K) fluorescence spectroscopy and decay curve results confirm that Cr3+ occupies the four lattice sites of Al3+ in the matrix. Additionally, the introduction of Ga3+ increases the full‐width at half‐maximum (FWHM) of the NIR spectrum from 100 to 300 nm without affecting the fluorescence efficiency; it also considerably increases spectral coverage. An experiment to evaluate the applicability of the novel NIR phosphors reveals that the sunlight‐converting film prepared by applying the material combination of BaMgGa3Al7O17:0.02Cr3+ is able to effectively promote the growth of Chlorella. In addition, the NIR pc‐LED with a BaMgGa3Al7O17:0.2Cr3+ basis and 395‐nm LED chip has been proven to be an excellent candidate for applications in NIR spectral detection and night‐vision technology.

An overshooting effect was observed during the swelling procedure of poly(dimethylaminoethyl methacrylate) (PDMAEMA) gel for the first time. The effects of the temperature, ionic strength, and pH on the overshooting effect of the PDMAEMA gel were investigated. We found that the overshooting effect of the gel could not be eliminated by changing the temperature; however, the overshooting effect was indiscernible in high-concentration NaCl solutions (>0.2 mol/L) and basic (pH 11.9) and acidic solutions (pH ¼ 2.1). The overshooting effect of the PDMAEMA gel was attributed to the dynamic conformational changes of the side chains of dimethylaminoethyl methacrylate (DMAEMA) units during the swelling of the gels. In the presence of NaCl or NaOH, the stretching of the macromolecular chains of the gels was disrupted. While in acidic solution, the protonation of tertiary amino groups in the DMAEMA units made the side chains of the DMAEMA units change from the cyclic conformation to the stretched one; this was analyzed with the aid of Fourier transform infrared spectroscopy.