| 
									
										
		  							 | 
          							
		  									  								 
		  									  							|
		  									  								 
		  									  							 | 
        						 
      						 
      					 | 
  					 
  					
    					 | 
   					 
   										
    					| Probing Acidic OER Mechanisms on Cobalt/Iridium-Based 
Electrocatalysts via In Situ Surface-Enhanced Raman 
Spectroscopy | 
  					 
  					  										
						| HU Ce-jun2, HU Yan-fang1*, XIE Wei3* | 
					 
															
						1. Hebei Chemical & Pharmaceutical College, Shijiazhuang 050026, China 
2. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China 
3. College of Chemistry, Nankai University, Tianjin 300071, China
  | 
					 
										
						 | 
					 
				 
				
				
					
						
							
								
									
										
											
                        					 
												
													
													    | 
													    	
														 | 
													 
																										
													
														
															
													
													    | 
													     		                            						                            																	    Abstract  The acidic oxygen evolution reaction (OER) is a core process in proton exchange membrane water electrolyzers. However, the highly corrosive environment and complex reaction pathways pose significant challenges for developing efficient catalysts. Understanding the dynamic evolution of catalytically active sites and the reaction mechanism under realistic operating conditions is crucial for designing highly stable acidic OER catalysts. In this work, highly active and stable CoIrOx catalysts were prepared via a displacement method. Electrokinetic studies revealed that during catalyst activation, cobalt leaching generates surface vacancies, which in turn expose iridium sites that are oxidized to the active Ir5+ phase, thereby promoting the reaction. In situ surface-enhanced Raman spectroscopy (SERS) combined with H/D isotope experiments confirmed that OOH is the key intermediate species in the acidic OER process. Furthermore, 18O isotope labeling was used to probe the dynamic changes in the catalyst's surface microstructure. A pronounced blue shift in the Ir—O vibrational peak at OER potentials indicated that the OER on CoIrOx follows a lattice oxygen oxidation mechanism (LOM). This work provides new insights into the reaction mechanisms of CoIr-based catalysts and offers a novel approach for exploring OER pathways.
																										     | 
														 
														
														
															| 
											   							Received: 2025-07-29    
						    						    							Accepted: 2025-09-09    
						    						    						    																				    
															 | 
														 
														 														
															| 
																
															 | 
														 
																																									    														
															| 
																Corresponding Authors:
																HU Yan-fang, XIE Wei   
																																 E-mail: yanfanghu@hebcpc.edu.cn; wei.xie@nankai.edu.cn
															    													     		
													     	 | 
														 
																																												 
															 | 
											
														 
														
													 
													
												 
												
												
													
														  
															 [1] Reier T, Nong H N, Teschner D, et al. Advanced Energy Materials, 2017, 7(1): 1601275.  
[2] Chen Y, Li H, Wang J, et al. Nature Communications, 2019, 10(1): 572.  
[3] Wu T, Sun S, Song J, et al. Nature Catalysis, 2019, 2(9): 763.  
[4] Ren X, Wei C, Sun Y, et al. Advanced Materials, 2020, 32(30): 2001292.  
[5] Pedersen A F, Escudero-Escribano M, Sebok B, et al. The Journal of Physical Chemistry B, 2018, 122(2): 878. 
[6] Lin Y, Tian Z, Zhang L, et al. Nature Communications, 2019, 10(1): 162.  
[7] Guo H, Fang Z, Li H, et al. ACS Nano, 2019, 13(11): 13225.  
[8] Strickler A L, Flores R A, King L A, et al. ACS Applied Materials & Interfaces, 2019, 11(37): 34059.  
[9] Pi Y, Shao Q, Wang P, et al. Advanced Functional Materials, 2017, 27(27): 1700886.  
[10] An L, Wei C, Lu M, et al. Advanced Materials, 2021, 33(20): 2006328.  
[11] Rossmeisl J, Qu Z W, Zhu H, et al. Journal of Electroanalytical Chemistry, 2007, 607(1): 83.  
[12] Bastús N G, Comenge J, Puntes V. Langmuir, 2011, 27(17): 11098.  
[13] Li J F, Huang Y F, Ding Y, et al. Nature, 2010, 464(7287): 392.  
[14] Hu Y F, Li Y L, Yu L F, et al. Chemical Science, 2022, 13: 11792.  
[15] Pavlovic Z, Ranjan C, Gao Q, et al. ACS Catalysis, 2016, 6(12): 8098.  
[16] Pavlovic Z, Ranjan C, Van Gastel M, et al. Chemical Communications, 2017, 53(92): 12414.  
[17] Saeed K H, Forster M, Li J F, et al. Chemical Communications, 2020, 56(7): 1129.
  | 
														 
														
													 
												 
												
													
														
															
																
																																																																																						
																				
																					| [1] | 
																					XU De-fang1, GUAN Hong-pu2, ZHAO Hua-min3, ZHANG Shu-juan3, ZHAO Yan-ru2*. Early Detection Method of Mechanical Damage of Yuluxiang Pear Based on SERS and Deep Learning[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(06): 1712-1718. | 
																				 
																			
																																																																																																									
																				
																					| [2] | 
																					JIANG Heng1, LÜ Zi-wei1, LI Yang2, DONG Tuo1*. A Novel Strategy for Viral Detection in Acute Respiratory Infections: Combining SERS With Machine Learning[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(05): 1217-1224. | 
																				 
																			
																																																																																																									
																				
																					| [3] | 
																					LIU Wen-bo, LI Han, XU Yuan-cong, LIU Meng-dong, WANG Hui-qin, LIN Tai-feng, ZHENG Da-wei, ZHANG Ping*. Rapid Detection of Bacterial Conjunctivitis Pathogens Using SERS@Au Microarray Chip[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(02): 476-482. | 
																				 
																			
																																																																																																									
																				
																					| [4] | 
																					WANG De-ying1, 2, SHENG Wan-li3, ZOU Ming-qiang1, PEI Jia-huan1, 2, LUO Yun-jing2, QI Xiao-hua1*. Research Progress of Detection Based on Hydrogel Surface Enhanced 
Raman Spectroscopy (SERS) Substrate[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(10): 2701-2708. | 
																				 
																			
																																																																																																									
																				
																					| [5] | 
																					ZHAO Jing-rui1, WANG Ya-min1, YUAN Yu-xun1, YU Jing1, ZHAO Ming-hui1, DONG Juan1, 3, SUN Jing-tao1, 2, 3, 4*. Study on SERS Detection of Ethyl Carbamate in Grape Spirit[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(09): 2467-2475. | 
																				 
																			
																																																																																																									
																				
																					| [6] | 
																					WEI Yu-lan, ZHANG Chen-jie, YUAN Ya-xian*, YAO Jian-lin*. In-Situ SERS Monitoring of SPR-Catalyzed Coupling Reaction of 
p-Nitroiodobenzene on Noble Metal Nanoparticles[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(09): 2482-2487. | 
																				 
																			
																																																																																																									
																				
																					| [7] | 
																					LI Chang-ming1, GU Yi-fan2, ZHANG Hong-chen1, SONG Shao-zhong3*, GAO Xun2*. The Surface Enhanced Raman Spectroscopy Characteristics of Cyromazine Molecule Based on Density Function Theory[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(06): 1566-1570. | 
																				 
																			
																																																																																																									
																				
																					| [8] | 
																					SI Min-zhen1, 2, WANG Min1, 2, LI Lun1, 2, YANG Yong-an1, 2, ZHONG Jia-ju3, YU Cheng-min3*. The Main Ingredients Analysis and Rapid Identification of Boletuses Based on Surface-Enhanced Raman Spectroscopy[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(06): 1648-1654. | 
																				 
																			
																																																																																																									
																				
																					| [9] | 
																					HUANG Li-jun1, ZHUANG Shun-qian2, FENG Yong-wei1, YANG Fang-wei2, SUN Zhen1, XIE Yun-fei2*, XUE Qing-hai1. Simultaneous Determination of Five Banned Sartan Compounds in Antihypertensive Health Food Using Thin-Layer Chromatography Combined With Surface-Enhanced Raman Spectroscopy (TLC-SERS)[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(05): 1354-1363. | 
																				 
																			
																																																																																																									
																				
																					| [10] | 
																					XING Hai-bo1, ZHENG Bo-wen1, LI Xin-yue1, HUANG Bo-tao2, XIANG Xiao2, HU Xiao-jun1*. Colorimetric and SERS Dual-Channel Sensing Detection of Pyrene in 
Water[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2024, 44(01): 95-102. | 
																				 
																			
																																																																																																									
																				
																					| [11] | 
																					LU Wen-jing, FANG Ya-ping, LIN Tai-feng, WANG Hui-qin, ZHENG Da-wei, ZHANG Ping*. Rapid Identification of the Raman Phenotypes of Breast Cancer Cell 
Derived Exosomes and the Relationship With Maternal Cells[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(12): 3840-3846. | 
																				 
																			
																																																																																																									
																				
																					| [12] | 
																					GUO He-yuanxi1, LI Li-jun1*, FENG Jun1, 2*, LIN Xin1, LI Rui1. A SERS-Aptsensor for Detection of Chloramphenicol Based on DNA  Hybridization Indicator and Silver Nanorod Array Chip[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(11): 3445-3451. | 
																				 
																			
																																																																																																									
																				
																					| [13] | 
																					LI Wen-wen1, 2, LONG Chang-jiang1, 2, 4*, LI Shan-jun1, 2, 3, 4, CHEN Hong1, 2, 4. Detection of Mixed Pesticide Residues of Prochloraz and Imazalil in 
Citrus Epidermis by Surface Enhanced Raman Spectroscopy[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(10): 3052-3058. | 
																				 
																			
																																																																																																									
																				
																					| [14] | 
																					ZHAO Ling-yi1, 2, YANG Xi3, WEI Yi4, YANG Rui-qin1, 2*, ZHAO Qian4, ZHANG Hong-wen4, CAI Wei-ping4. SERS Detection and Efficient Identification of Heroin and Its Metabolites Based on Au/SiO2 Composite Nanosphere Array[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(10): 3150-3157. | 
																				 
																			
																																																																																																									
																				
																					| [15] | 
																					HUANG Bao-kun1*, ZHAO Qian-nan2, LIU Ye-fan2, ZHU Lin1, ZHANG Hong2, ZHANG Yun-hong3*, LIU Yan4*. In Situ Detection of Fuel Engine Exhaust Components by Raman 
Integrating Sphere[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(10): 3310-3313. | 
																				 
																			
																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																										 
														 | 
													 
												 
											 
											
											 
											
											 
										 
									 | 
								 
							 
						 | 
					 
				 
			
		 |