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Developing efficient and affordable electrocatalysts for oxygen reduction reaction (ORR) is very important for next-generation energy conversion and storage devices. Herein, N-doped carbon materials with high N-doping level (5.02 at%) and hierarchically porous structure (H-NHPC) were fabricated by pyrolysis of inexpensive beancurd soaked with urea and NaCl, which was employed as an extra nitrogen resource and a green template to control the morphology and porosity, respectively. The as-prepared H-NHPC exhibited better ORR catalytic activity than the benchmark Pt/C electrocatalysts and most of other biomass-driven nitrogen-doped carbon materials in alkaline medium. The excellent catalytic activity of H-NHPC was attributed to its high content of catalytic active species such as pyridinic-N and graphitic-N, large surface area (988.2 m 2 g −1 ) and abundant porosity ranging from micro-to meso-and macro-scale for efficient mass transfer. Furthermore, the Zn-air battery (ZAB) assembled with H-NHPC as the air electrode displayed higher power-density, larger specific-capacity and better rate-capability than the Pt/C-based ZAB, showing great application perspective in metal-air batteries.

Development of efficient electrocatalysts with high catalytic performance and low cost for promoting oxygen reduction reaction (ORR) in both alkaline and acidic media is highly desired yet a challenging. Here, graphene-like nitrogen and phosphorus dual-doped porous carbon nanosheets are prepared by calcinating a homogeneous mixture of glucose, melamine and phosphoric acid with montmorillonite as the nanoreactor. The as-prepared N,P dual-doped porous carbon nanosheets show satisfactory ORR catalytic performance in both alkaline and acidic media due to the synergistic effect of N, P dual-doping, abundant micro-/meso-pores and large specific surface area (835.91 m 2 g À1 ). Its catalytic activity in 0.1 M KOH outperforms the bench-mark Pt/C catalyst with more positive half-wave potential and larger diffusion current density; its catalytic activity in 0.1 M HClO 4 is comparable to that of Pt/C. Furthermore, it exhibits excellent tolerance towards methanol crossover and long-term stability, showing great promise as an alternative to Pt/C for application in fuel cells and metal-air batteries. Results and DiscussionN,P-CS was synthesized via a MMT-assisted pyrolysis route as depicted in Figure 1(a). MMT is a typical layered aluminosilicate with strong chemical bonds in-plane but weak van der Waals and electrostatic forces between the layers. The interlayer [a] Prof.

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Hybrid structures of quantum dots (QDs) on two-dimensional materials have aroused great interest because of their high absorbance properties and tunable wavelength detection ranges. In this work, 1.44 times the photoresponse bandwidth of PbSe QDs on atomic-layered GeS hybrid structure devices is achieved compared with pure GeS devices due to the transfer of photogenerated carriers between the PbSe QDs and the GeS film. A doubling of the peak photoresponsivity is obtained at a wavelength of 635 nm, and the detectivity of the hybrid devices increases by 39.5 and 27.4 times under 808 and 980 nm illumination, respectively. Additionally, tripling of the carrier mobility is measured in the hybrid devices (165.2 cm2 V−1 s−1) compared with that of pure atomic-layered GeS devices (54.2 cm2 V−1 s−1). The concentration of PbSe QDs on the GeS films is optimized for the highest photoresponsivity and carrier mobility of the hybrid devices. The results indicate that a hybrid structure of QDs on atomic-layered materials is a promising way to enhance photodetection.