The engineering of polymorph heterojunctions is an essential approach for improving the catalytic kinetics for water electrolysis. Yet, efficient tailoring tactics with component regulation and optimization in the microenvironment are highly desired but a huge challenge. Herein, the design and construction of a kind of nickel phosphide polymorph heterojunction (Ni₂P/Ni₃P) by an in situ Cr-induced structural transition method is presented, which needs overpotentials of only 108 and 270 mV to reach 10 mA cm^–2 for the hydrogen evolution reactions (HER) and oxygen evolution reactions (OER), respectively. It exhibits superior bifunctional activity for overall water splitting, which reaches a current density of 10 mA cm^–2 at a cell voltage of 1.56 V. The above current density is 9.1 times higher than that of the Pt/C@NF₍₋₎//RuO₂@NF₍₊₎ pair at the same cell voltage. The in situ induced phase transition approach is beneficial for Cr–Ni₂P/Ni₃P@NF with strong interfacial coupling and more active sites constructed by the amorphous region, which optimize the d-band center of the electrocatalyst and lead to charge redistribution at the interfaces of Ni₂P/Ni₃P, regulating the adsorption of H* and OOH* intermediation. This work provides inspiration for optimizing the catalytic activity through the engineering of polymorph heterojunctions by in situ metal-induced structural transition for bifunctional transition metal compound electrocatalysts.

中文翻译：

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通过原位 Cr 诱导结构转变构建磷酸镍多晶型异质结以增强双功能电化学水分解

多晶型异质结的工程是提高水电解催化动力学的重要方法。然而，在微环境中进行组件调节和优化的有效定制策略是非常需要的，但也是一个巨大的挑战。在此，提出了一种通过原位Cr诱导结构转变方法设计和构建的一种磷化镍多晶型异质结（Ni ₂ P/Ni ₃ P），该异质结仅需要108和270 mV的过电位即可达到10 mA cm ^–2分别代表析氢反应 (HER) 和析氧反应 (OER)。它表现出优异的整体水分解双功能活性，在1.56 V的电池电压下达到10 mA cm ^–2的电流密度。上述电流密度是Pt/C@NF ₍₋₎ /的9.1倍/RuO ₂ @NF ₍₊₎对在相同的电池电压下。原位诱导相变方法有利于Cr-Ni ₂ P/Ni ₃ P@NF具有强界面耦合和非晶区构造的更多活性位点，从而优化了电催化剂的d带中心并导致电荷重新分布在Ni ₂ P/Ni ₃ P界面上，调节H*和OOH*中介的吸附。这项工作为双功能过渡金属化合物电催化剂通过原位金属诱导结构转变来设计多晶型异质结来优化催化活性提供了灵感。