Ultrafast Thermal Synthesis of Non-Noble Metal-Based Electrocatalysts for Overall Water Splitting

Abstract

Non-noble metal-based electrocatalysts have attracted extensive interest due to their low-cost, earth-abundance, and highly efficient catalytic performance as alternatives to noble metal counterparts. However, conventional approaches to synthesize electrocatalysts can endure overlong synthesis time with throughput degradation. Here, we demonstrate an ultrafast thermal method to synthesize non-noble metal-based electrocatalysts for overall water splitting. The method can be extensively used for metal-based catalysts, including metal oxides, metal carbides, alloys, and their composites. Among them, we select two outstanding electrocatalysts as examples for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hybrid structure of nickel oxides and molybdenum carbides on activated carbon felt (Ni–Mo@ACF) for HER shows remarkable catalytic activity with a low overpotential of 87 mV and an excellent durability for 48 h at a current density of 10 mA cm–2. The NiFe alloy nanosheets on activated carbon felt (NiFe@ACF) for OER show superb catalytic activity with a low overpotential of 270 mV and great durability for 48 h at a current density of 10 mA cm–2. Consequently, an overall water splitter assembled with Ni–Mo@ACF as the cathode and NiFe@ACF as the anode only requires a low cell voltage of 1.60 V to drive a current density of 10 mA cm–2 with excellent durability for 36 h, which is the best among non-noble metal-based electrocatalysts reported so far. This work offers an approach for the ultrafast and facile synthesis of non-noble metal-based electrocatalysts for water splitting and other applications.

On the Effect of the Nature of Carbon Nanostructures on the Activity of Bifunctional Catalysts Based on Manganese Oxide Nanowires

“…In the case of OER, the reverse of the four-electron ORR pathway was considered as the predominant mechanism (inverse of Equations ( 1)-( 4)). The Tafel slope of MONW (73 mV dec −1 ) suggests that the third step (inverse of Equation ( 2)) is the rate-limiting step on this material [53]. In rGO, on the other hand, the Tafel slope of 131 mV dec −1 suggests that the first step, i.e., the protonation of an adsorbed hydroxyl group (inverse of Equation ( 4)), which has a theoretical Tafel slope of 120 mV dec −1 [54].…”