Abstract Sunlight-driven photocatalytic water-splitting for hydrogen (H2) evolution is a desirable strategy to utilize solar energy. However, this strategy is restricted by insufficient light harvesting and high photogenerated electron–hole recombination rates of TiO2-based photocatalysts. Here, a graphene-modified WO3/TiO2 step-scheme heterojunction (S-scheme heterojunction) composite photocatalyst was fabricated by a facile one-step hydrothermal method. In the ternary composite, TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide (rGO) and formed a novel S-scheme heterojunction. Moreover, rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO. The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes. This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites. Thus, the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8 μmol g−1h−1, which was approximately 3.5-fold that of pure TiO2. This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals, but also provides new insights into the design of novel heterojunction photocatalysts.

中文翻译：

---

通过石墨烯改性提高 WO3/TiO2 阶梯式异质结的光催化产氢活性

摘要 阳光驱动的光催化分解水分解氢 (H2) 是利用太阳能的理想策略。然而，这种策略受到二氧化钛基光催化剂的光收集不足和光生电子-空穴复合率高的限制。在这里，通过简便的一步水热法制备了石墨烯改性的 WO3/TiO2 阶梯式异质结（S 式异质结）复合光催化剂。在三元复合材料中，TiO2 和 WO3 纳米颗粒紧密粘附在还原氧化石墨烯 (rGO) 上并形成新型 S 型异质结。而且，复合材料中的 rGO 不仅提供了丰富的吸附和催化活性位点作为理想的载体，而且通过在 TiO2 和 rGO 之间形成肖特基结，促进了电子从 TiO2 导带的分离和转移。WO3和TiO2之间形成的S型异质结和TiO2和石墨烯片之间形成的肖特基异质结的正协同效应抑制了相对有用的电子和空穴的复合。这种效应还增强了光收集并促进了活性位点的还原反应。因此，新型三元 WO3/TiO2/rGO 复合材料表现出显着增强的光催化析氢速率 245.8 μmol g-1h-1，约为纯 TiO2 的 3.5 倍。