Highly efficient earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are of great importance for renewable energy conversion systems. Herein, guided by theoretical calculations, we demonstrate highly efficient water splitting in alkaline solution using quarternary mixed nickel iron phosphosulfide (Ni_1–xFe_xPS₃) nanosheets (NSs), even though neither NiPS₃ nor FePS₃ is a good HER (or OER) electrocatalyst. With tuned electronic structure and improved electrical conductivity induced by mixing appropriate amount of Fe into NiPS₃, Ni_0.9Fe_0.1PS₃ NSs display excellent HER activity (an overpotential of 72 mV vs reversible hydrogen electrode (RHE) at a geometric catalytic current density of −10 mA cm^–2 and a Tafel slope of 73 mV dec^–1), which is among the best HER catalysts under alkaline conditions. Ni_0.9Fe_0.1PS₃ NSs also show a good apparent OER activity (an overpotential of 329 mV vs RHE at a catalytic current density of 20 mA cm^–2 and a Tafel slope of 69 mV dec^–1), although structural investigation indicates the formation of Ni(Fe)OOH and Ni(Fe)(OH)₂ layers on the catalyst surface after OER reactions as likely the real active species. These mixed nickel iron phosphosulfide non-precious-metal electrocatalysts with enhanced intrinsic activity and long-term stability and durability should have great potential in overall water-splitting applications.

中文翻译：

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调节混合的磷硫化铁镍纳米片电催化剂以增强氢气和氧气的释放

对于氢气释放反应（HER）和氧气释放反应（OER）而言，高效的富含地球的电催化剂对于可再生能源转换系统至关重要。在本文中，以理论计算为指导，即使使用NiPS ₃和FePS ₃都不是良好的HER ，我们也证明了使用季铵混合磷化镍铁（Ni _{1– x} Fe _x PS ₃）纳米片（NSs）在碱性溶液中的高效水分解。或OER）电催化剂。通过将适当量的Fe掺入NiPS _3中，可调节电子结构并改善电导率，Ni _0.9 Fe _0.1 PS ₃NSs显示出出色的HER活性（在-10 mA cm ^–2的几何催化电流密度和73 mV dec ^–1的Tafel斜率下，与可逆氢电极（RHE）相比，过电势为72 mV ），这是最好的HER催化剂之一在碱性条件下。Ni _0.9 Fe _0.1 PS ₃ NSs还显示出良好的表观OER活性（在20 mA cm ^–2的催化电流密度下，Tafel斜率为69 mV dec ^–1时，RHE的过电势为329 mV ）。 Ni（Fe）OOH和Ni（Fe）（OH）_2的形成OER反应后，催化剂表面上的有机层可能是真正的活性物质。这些具有增强的内在活性以及长期稳定性和耐久性的混合镍铁磷硫化物非贵金属电催化剂在整个水分解应用中应具有巨大的潜力。