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Wood materials are being reinvented to carry superior properties for a variety of new applications. Cutting‐edge nanomanufacturing transforms traditional bulky and low‐value woods into advanced materials that have desired structures, durability, and functions to replace nonrenewable plastics, polymers, and metals. Here, a first prospect report on how novel nanowood materials have been developed and applied in water and associated industries is provided, wherein their unique features and promises are discussed. First, the unique hierarchical structure and associated properties of the material are introduced, and then how such features can be harnessed and modified by either bottom‐up or top‐down manufacturing to enable different functions for water filtration, chemical adsorption and catalysis, energy and resource recovery, as well as energy‐efficient desalination and environmental cleanup are discussed. The study recognizes that this is a nascent but very promising field; therefore, insights are offered to encourage more research and development. Trees harness solar energy and CO2 and provide abundant carbon‐negative materials. Once harvested and utilized, it is believed that advanced wood materials will play a vital role in enabling a circular water economy. 

Hydrogen evolution is not a spontaneous reaction, so current electrochemical H 2 systems either require an external power supply or use complex photocathodes. We present in this study that by using electrical decoupling, H 2 can be produced spontaneously from wastewater. A power management system (PMS) circuit was deployed to decouple bioanode organic oxidation from abiotic cathode proton reduction in the same electrolyte. The special PMS consisted of a boost converter and an electromagnetic transformer, which harvested energy from the anode followed by voltage magnification from 0.35 V to 2.2–2.5 V, enabling in situ H 2 evolution for over 96 h without consuming any external energy. This proof-of-concept demonstrated a cathode faradaic efficiency of 91.3% and a maximum overall H 2 conversion efficiency of 28.9%. This approach allows true self-sustaining wastewater to H 2 evolution, and the system performance can be improved via the PMS and reactor optimization. 

Unbiased photoelectrochemical hydrogen production with high efficiency and durability is highly desired for solar energy storage. Here, we report a microbial photoelectrochemical (MPEC) system that demonstrated superior performance when equipped with bioanodes and black silicon photocathode with a unique “Swiss-cheese” interface. The MPEC utilizes the chemical energy embedded in wastewater organics to boost solar H 2 production, which overcomes barriers on anode H 2 O oxidation. Without any bias, the MPEC generates a record photocurrent (up to 23 mA cm −2 ) and retains prolonged stability for over 90 hours with high Faradaic efficiency (96–99%). The calculated turnover number for MoS x catalyst during a 90 h period is 495 471 with an average frequency of 1.53 s −1 . The system replaced pure water on the anode with actual wastewater and achieved waste organic removal up to 16 kg COD m −2 photocathode per day. Cost credits from concurrent wastewater treatment and low-cost design make photoelectrochemical H 2 production practical for the first time.