Wood-Structured Nanomaterials as Highly Efficient, Self-Standing Electrocatalysts for Water Splitting.

Electrocatalytic water splitting (EWS) driven by renewable energy is widely considered an environmentally friendly and sustainable approach for generating hydrogen (H2), an ideal energy carrier for the future. However, the efficiency and economic viability of large-scale water electrolysis depend on electrocatalysts that can efficiently accelerate the electrochemical reactions taking place at the two electrodes. Wood-derived nanomaterials are well-suited for serving as EWS catalysts because of their hierarchically porous structure with high surface area and low tortuosity, compositional tunability, cost-effectiveness, and self-standing integral electrode configuration. Here, recent advancements in the design and synthesis of wood-structured nanomaterials serving as advanced electrocatalysts for water splitting are summarized. First, the design principles and corresponding strategies toward highly effective wood-structured electrocatalysts (WSECs) are emphasized. Then, a comprehensive overview of current findings on WSECs, encompassing diverse structural designs and functionalities such as supported-metal nanoparticles (NPs), single-atom catalysts (SACs), metal compounds, and heterostructured electrocatalysts based on engineered wood hosts are presented. Subsequently, the application of these WSECs in various aspects of water splitting, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), overall water splitting (OWS), and hybrid water electrolysis (HWE) are explored. Finally, the prospects, challenges, and opportunities associated with the broad application of WSECs are briefly discussed. This review aims to provide a comprehensive understanding of the ongoing developments in water-splitting catalysts, along with outlining design principles for the future development of WSECs.

Hollow Nitrogen-Doped porous carbon spheres decorated with atomically dispersed Ni-N3 sites for efficient electrocatalytic CO2 reduction.

Hollow nitrogen-doped porous carbon spheres (HNCS) with plentiful coordination N sites, high surface area, and superior electrical conductivity are ideal catalyst supports due to their easily access of reactants to active sites and excellent stability. To date, nevertheless, little has been reported on HNCS as supports to metal-single-atomic sites for CO2 reduction (CO2R). Here we report our findings in preparation of nickel-single-atom catalysts anchored on HNCS (Ni SAC@HNCS) for highly efficient CO2R. The obtained Ni SAC@HNCS catalyst exhibits excellent activity and selectivity for the electrocatalytic CO2-to-CO conversion, achieving a Faradaic efficiency (FE) of 95.2% and a partial current density of 20.2 mA cm-2. When applied to a flow cell, the Ni SAC@HNCS delivers above 95% FECO over a wide potential range and a peak FECO of 99%. Further, there is no obvious degradation in FECO and the current for CO production during continuous electrocatalysis of 9 h, suggesting good stability of Ni SAC@HNCS.