Two‐dimensional covalent organic frameworks (2D‐COFs) have emerged as attractive platforms for solar‐to‐chemical energy conversion. In this study, we have implemented a gradient heating strategy to synthesize a sp2‐carbon‐linked triazine‐based COF, COF‐JLU100, exhibiting high crystallinity, large surface area, good durability and carrier mobility for solar‐driven photocatalytic hydrogen evolution. The Pt‐doped COF‐JLU100 demonstrated a high hydrogen evolution rate of over 100 000 μmol g−1 h−1 for water splitting under visible‐light illumination (λ>420 nm). Experimental and theoretical studies corroborate that the cyano‐vinylene segments in COF‐JLU100 extend the π‐delocalization and enable fast charge transfer and separation rates as well as good dispersion in water. Moreover, COF‐JLU100 can be prepared by low‐cost and easily available monomers and has excellent stability, which is desirable for practical solar‐driven hydrogen production.

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Visible Light Communications (VLC) is emerging as an appealing technology to complement WiFi in indoor environments. Yet maintaining VLC performance under link dynamics remains a challenging problem. In this paper, we build a VLC software-radio testbed and examine VLC channel dynamics through comprehensive measurement. We find minor device movement or orientation change can cause the VLC link SNR to vary by tens of dB even within one packet duration, which renders existing WiFi rate adaptation protocols ineffective. We thus propose a new mechanism, DLit, that leverages two unique properties of VLC links (predictability and fullduplex) to realize fine-grained, in-frame rate adaptation. Our prototype implementation and experiments demonstrate that DLit achieves near-optimal performance for mobile VLC usage cases, and outperforms conventional packet-level adaptation schemes by multiple folds.

It has been shown in the literature that network coding can improve the transmission efficiency of wireless broadcasting as compared to traditional ARQ schemes. In this paper, we propose an improved network coding scheme that can asymptotically achieve the theoretical lower bound on transmission overhead for a sufficiently large number of information blocks. The proposed scheme makes use of an index allocation algorithm that distributes information blocks that have been erased during transmission into a minimum number of encoding sets , where each set represents the erased blocks to be jointly network encoded and retransmitted. Numerical results show that the proposed scheme enables higher transmission efficiencies than traditional ARQ, and previously proposed networks coding schemes for wireless broadcasting.