Defect‐Engineered (Ni 2 V 2 O 7 ) x /(FeVO
P. B. Vidyashree, S. Ashoka, K. Yogesh, N. S. VenkataramananABSTRACT
Co‐electrolysis of water and formaldehyde holds significant potential for applications in energy conversion devices, chemical synthesis, and environmental remediation, all while reducing energy consumption. However, designing efficient and abundant electrocatalysts remains a major challenge. Herein, we synthesized a trifunctional hetero‐structured electrocatalyst, (Ni 2 V 2 O 7 ) x /(FeVO 4 ) y analogues, using a simple precipitation method followed by thermal treatment. This approach generates a high concentration of surface Ni 3+ ‐ions and structural defect sites, significantly enhancing the electrochemical surface area (ECSA) and reducing charge transfer resistance ( R ct ), both critical for improving the co‐electrolysis of formaldehyde and water. The optimized heterostructure (Ni 2 V 2 O 7 ) 0.7 /(FeVO 4 ) 0.3 requires an overpotential of 1.597 V versus reversible hydrogen electrode (RHE) to achieve a current density of 500 mA cm − 2 in 1 M KOH, showing a mass activity of 3.73 A g − 1 and a turnover frequency (TOF) of 0.00273 s − 1 . In the presence of formaldehyde, the potential drops to 1.531 V, with enhanced mass activity of 166.66 A g − 1 and a TOF of 0.1232 s − 1 . In a single‐stack cell, the heterostructure needs only 1.28 V at 10 mA cm − 2 with formaldehyde, 410 mV lower than without it, yielding an energy‐saving efficiency of 24.4%.