Lin Qian, Guo Daying, Zhou Ling, Yang Lin, Jin Huile, Li Jun, Fang Guoyong, Chen Xi'an, Wang Shun
Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, China 325035.
ACS Nano. 2022 Sep 27;16(9):15460-15470. doi: 10.1021/acsnano.2c07588. Epub 2022 Sep 12.
The construction of heterostructures is one of the most promising strategies for engineering interfaces of catalysts to perform high-efficiency oxygen evolution reaction (OER). However, accurately tuning heterostructures' interface during operation remains a challenge. Herein, we fabricated the needled-like heterostructure CoS/Co(OH)F supported on flexible carbon fiber cloth an atomic substitution strategy, in which sulfur atoms are simultaneously grafted into F vacancies after the partial removal of F atoms from Co(OH)F during the electrodeposition, thus achieving the growth of cobalt sulfide on the interface of Co(OH)F. This electrocatalyst with such design exhibits the following advantages: (1) The lattice distortion caused by atomic substitution leads to the increase of active sites; (2) CoS constructed on the surface of Co(OH)F by the atomic replacement strategy optimizes the adsorption (OH) and desorption (O) energy in the OER process; (3) the needle-like structure possesses the tip-enhanced local electric field effect. As a result, the CoS/Co(OH)F/CC catalyst exhibits very high OER catalytic performance with an overpotential of 269 mV at a current density of 10 mA cm and a Tafel slope of 71 mV dec. The asymmetric electrode shows superior catalytic activity and stability in overall water splitting. The catalytic mechanism of these highly efficient CoS/Co(OH)F/CC catalysts was investigated DFT theoretical calculations and characterizations. This atomic substitution strategy displays universality for other transition metal sulfides (metal = Ni, Mn, Cu).
构建异质结构是设计催化剂界面以实现高效析氧反应（OER）最具前景的策略之一。然而，在运行过程中精确调控异质结构的界面仍然是一个挑战。在此，我们通过原子取代策略制备了负载在柔性碳纤维布上的针状异质结构CoS/Co(OH)F，即在电沉积过程中，Co(OH)F中的F原子部分去除后，硫原子同时接枝到F空位中，从而实现了硫化钴在Co(OH)F界面上的生长。这种具有上述设计的电催化剂具有以下优点：（1）原子取代引起的晶格畸变导致活性位点增加；（2）通过原子取代策略在Co(OH)F表面构建的CoS优化了OER过程中的吸附（OH）和解吸（O）能量；（3）针状结构具有尖端增强的局部电场效应。结果，CoS/Co(OH)F/CC催化剂表现出非常高的OER催化性能，在电流密度为10 mA cm时过电位为269 mV，塔菲尔斜率为71 mV dec。该不对称电极在全水解中表现出优异的催化活性和稳定性。通过DFT理论计算和表征研究了这些高效CoS/Co(OH)F/CC催化剂的催化机理。这种原子取代策略对其他过渡金属硫化物（金属 = Ni、Mn、Cu）具有通用性。
