Revealing the role of 1T- & 2H- molybdenum Disulfide/Nickel sulfide heterojunction for efficient overall water splitting

In the ongoing quest for cost-effective and durable electrocatalysts for hydrogen production-a critical element of sustainable energy transformation-the 1T phase of Molybdenum Disulfide (MoS₂) faces challenges due to its thermodynamic instability and the trade-off between efficiency and durability. Conversely, the 2H phase of MoS₂, often disregarded in favor of the metallic 1T phase, suffers from its inert nature and limited active sites. To overcome these limitations, this study employs a straightforward hydrothermal synthesis strategy that couples both 1T and 2H phases of MoS₂ with Ni₃S₂, forming 1T- and 2H- MoS₂/Ni₃S₂ heterojunctions. Enhanced by Ni₃S₂'s abundant active sites, improved electron transport capabilities, synergistic interface effects, and better structural stability, these heterojunctions achieve a high current density exceeding 500 mA cm^-2 at low overpotentials, along with prolonged durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes. Remarkably, an electrolyzer assembly utilizing 1T-MoS₂/Ni₃S₂ as the cathode and 2H-MoS₂/Ni₃S₂ as the anode demonstrates a competitive voltage of 1.58 V at 20 mA cm^-2, showcasing superior performance in overall water splitting compared to other non-noble metal-based electrocatalysts. This study not only offers a viable method for synthesizing efficient and stable electrocatalysts for water splitting using transition metal-based heterogeneous structures but also addresses the fundamental challenges associated with 1T and 2H phases of MoS₂.