Li Guoning, Liu Faming, Ma Weiyang, Li Hui, Li Shijie
School of Thermal Engineering, Shandong Jianzhu University, Jinan 250101, China.
Molecules. 2023 Jul 26;28(15):5648. doi: 10.3390/molecules28155648.
Exploring low-cost and eco-friendly bifunctional electrocatalysts of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolytes is still highly desired, and is crucial for water electrolysis and sustainable hydrogen generation. In this work, we report a facile pyrolysis-oxidation strategy to convert by-product lignin into bifunctional OER/HER electrocatalysts (Co/CoO-NPC-400) composed of Co/CoO anchored on N-doped carbon with a surface of rich oxygen vacancies and oxygen-containing groups. The co-pyrolysis of lignin and NHCl can achieve a N-doped carbon matrix with a hierarchical pore structure, while the air-annealing process can induce the formation of oxygen-containing groups and oxygen vacancies. Owing to its surface properties, hierarchical pore structure and multiple active components, the constructed Co/CoO-NPC-400 possesses bifunctional catalytic activity and superior stability for OER/HER, especially for unexpected OER activity with a high current density of about 320 mA∙cm at a potential of 1.8 V (vs. RHE). Water electrolysis using Co/CoO-NPC-400 as both the anode and the cathode needs a cell voltage of 1.95 and 2.5 V to attain about 10 and 400 mA∙cm in 1 M KOH. This work not only provides a general strategy for the preparation of carbon-supported electrocatalysts for water splitting, but also opens up a new avenue for the utilization of lignin.
探索用于碱性电解质中析氧反应（OER）和析氢反应（HER）的低成本且环保的双功能电催化剂仍然是人们迫切期望的，这对于水电解和可持续制氢至关重要。在这项工作中，我们报道了一种简便的热解-氧化策略，将副产物木质素转化为双功能OER/HER电催化剂（Co/CoO-NPC-400），该催化剂由锚定在具有丰富氧空位和含氧基团表面的氮掺杂碳上的Co/CoO组成。木质素与NHCl的共热解可以实现具有分级孔结构的氮掺杂碳基质，而空气退火过程可以诱导含氧基团和氧空位的形成。由于其表面性质、分级孔结构和多种活性成分，构建的Co/CoO-NPC-400对OER/HER具有双功能催化活性和优异的稳定性，特别是在1.8 V（相对于可逆氢电极，RHE）的电位下具有约320 mA∙cm的高电流密度的意外OER活性。使用Co/CoO-NPC-400作为阳极和阴极的水电解在1 M KOH中需要1.95和2.5 V的电池电压才能达到约10和400 mA∙cm。这项工作不仅为制备用于水分解的碳负载电催化剂提供了一种通用策略，还为木质素的利用开辟了一条新途径。
